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[PATCH v2 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. 147+ messages / 3 participants [nested] [flat]
* [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; 147+ 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] 147+ messages in thread
* [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; 147+ 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] 147+ 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; 147+ 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] 147+ messages in thread
* [PATCH v9 2/2] wip: report nanoseconds in pg_test_timing @ 2023-01-16 19:19 Andres Freund <[email protected]> 0 siblings, 0 replies; 147+ messages in thread From: Andres Freund @ 2023-01-16 19:19 UTC (permalink / raw) This commit also updates pg_test_timing's documentation: - compare EXPLAIN (ANALYZE, TIMING ON/OFF) instead of comparing performance of of statement with/without EXPLAIN ANALYZE - explain the 2x overhead (due to two timestamp acquisitions per row) - remove old section about old versions of linux - I couldn't update the numbers, and it's old enough nobody would care --- src/bin/pg_test_timing/pg_test_timing.c | 74 +++++++++------ doc/src/sgml/ref/pgtesttiming.sgml | 117 ++++++++++-------------- 2 files changed, 95 insertions(+), 96 deletions(-) diff --git a/src/bin/pg_test_timing/pg_test_timing.c b/src/bin/pg_test_timing/pg_test_timing.c index c29d6f87629..e20718669a5 100644 --- a/src/bin/pg_test_timing/pg_test_timing.c +++ b/src/bin/pg_test_timing/pg_test_timing.c @@ -19,8 +19,8 @@ static void handle_args(int argc, char *argv[]); static uint64 test_timing(unsigned int duration); static void output(uint64 loop_count); -/* record duration in powers of 2 microseconds */ -long long int histogram[32]; +/* record duration in powers of 2 nanoseconds */ +uint64 histogram[64]; int main(int argc, char *argv[]) @@ -121,35 +121,48 @@ handle_args(int argc, char *argv[]) static uint64 test_timing(unsigned int duration) { - uint64 total_time; - int64 time_elapsed = 0; uint64 loop_count = 0; - uint64 prev, - cur; + instr_time until_time, + total_time; instr_time start_time, - end_time, - temp; - - total_time = duration > 0 ? duration * INT64CONST(1000000) : 0; + end_time; + instr_time cur; INSTR_TIME_SET_CURRENT(start_time); - cur = INSTR_TIME_GET_MICROSEC(start_time); - while (time_elapsed < total_time) + /* + * To reduce loop overhead, check loop condition in instr_time domain. + */ + INSTR_TIME_SET_SECONDS(total_time, duration); + until_time = start_time; + INSTR_TIME_ADD(until_time, total_time); + + cur = start_time; + + while (INSTR_TIME_IS_LT(cur, until_time)) { - int32 diff, - bits = 0; + instr_time temp; + instr_time prev; + int64 diff; + int32 bits = 0; prev = cur; - INSTR_TIME_SET_CURRENT(temp); - cur = INSTR_TIME_GET_MICROSEC(temp); - diff = cur - prev; + INSTR_TIME_SET_CURRENT(cur); + temp = cur; + INSTR_TIME_SUBTRACT(temp, prev); + diff = INSTR_TIME_GET_NANOSEC(temp); /* Did time go backwards? */ - if (diff < 0) + if (unlikely(diff <= 0)) { + /* can't do anything with that measurement */ + if (diff == 0) + { + loop_count++; + continue; + } fprintf(stderr, _("Detected clock going backwards in time.\n")); - fprintf(stderr, _("Time warp: %d ms\n"), diff); + fprintf(stderr, _("Time warp: %lld ns\n"), (long long) diff); exit(1); } @@ -164,8 +177,6 @@ test_timing(unsigned int duration) histogram[bits]++; loop_count++; - INSTR_TIME_SUBTRACT(temp, start_time); - time_elapsed = INSTR_TIME_GET_MICROSEC(temp); } INSTR_TIME_SET_CURRENT(end_time); @@ -173,7 +184,7 @@ test_timing(unsigned int duration) INSTR_TIME_SUBTRACT(end_time, start_time); printf(_("Per loop time including overhead: %0.2f ns\n"), - INSTR_TIME_GET_DOUBLE(end_time) * 1e9 / loop_count); + (INSTR_TIME_GET_DOUBLE(end_time) * NS_PER_S) / loop_count); return loop_count; } @@ -181,9 +192,10 @@ test_timing(unsigned int duration) static void output(uint64 loop_count) { - int64 max_bit = 31, + int64 low_bit = 0, + max_bit = 63, i; - char *header1 = _("< us"); + char *header1 = _("< ns"); char *header2 = /* xgettext:no-c-format */ _("% of total"); char *header3 = _("count"); int len1 = strlen(header1); @@ -194,15 +206,19 @@ output(uint64 loop_count) while (max_bit > 0 && histogram[max_bit] == 0) max_bit--; + /* find lowest bit value */ + while (low_bit < max_bit && histogram[low_bit] == 0) + low_bit++; + printf(_("Histogram of timing durations:\n")); printf("%*s %*s %*s\n", - Max(6, len1), header1, + Max(9, len1), header1, Max(10, len2), header2, Max(10, len3), header3); - for (i = 0; i <= max_bit; i++) - printf("%*ld %*.5f %*lld\n", - Max(6, len1), 1l << i, + for (i = low_bit; i <= max_bit; i++) + printf("%*ld %*.5f %*llu\n", + Max(9, len1), 1l << i, Max(10, len2) - 1, (double) histogram[i] * 100 / loop_count, - Max(10, len3), histogram[i]); + Max(10, len3), (long long unsigned) histogram[i]); } diff --git a/doc/src/sgml/ref/pgtesttiming.sgml b/doc/src/sgml/ref/pgtesttiming.sgml index a5eb3aa25e0..7e0266cf58b 100644 --- a/doc/src/sgml/ref/pgtesttiming.sgml +++ b/doc/src/sgml/ref/pgtesttiming.sgml @@ -93,28 +93,34 @@ PostgreSQL documentation <para> Good results will show most (>90%) individual timing calls take less than - one microsecond. Average per loop overhead will be even lower, below 100 - nanoseconds. This example from an Intel i7-860 system using a TSC clock - source shows excellent performance: + one microsecond (1000 nanoseconds). Average per loop overhead will be even + lower, below 100 nanoseconds. This example from an Intel i9-9880H system + using a TSC clock source shows excellent performance: <screen><![CDATA[ Testing timing overhead for 3 seconds. -Per loop time including overhead: 35.96 ns +Per loop time including overhead: 13.74 ns Histogram of timing durations: - < us % of total count - 1 96.40465 80435604 - 2 3.59518 2999652 - 4 0.00015 126 - 8 0.00002 13 - 16 0.00000 2 + < ns % of total count + 16 97.00221 211857215 + 32 2.99555 6542412 + 64 0.00115 2505 + 128 0.00035 759 + 256 0.00004 78 + 512 0.00000 3 + 1024 0.00000 4 + 2048 0.00034 732 + 4096 0.00000 6 + 8192 0.00000 8 + 16384 0.00019 409 + 32768 0.00018 403 + 65536 0.00000 1 ]]></screen> </para> <para> - Note that different units are used for the per loop time than the - histogram. The loop can have resolution within a few nanoseconds (ns), - while the individual timing calls can only resolve down to one microsecond - (us). + Note that the accuracy of the histogram entries may be lower than the + per loop time. </para> </refsect2> @@ -125,24 +131,25 @@ Histogram of timing durations: When the query executor is running a statement using <command>EXPLAIN ANALYZE</command>, individual operations are timed as well as showing a summary. The overhead of your system can be checked by - counting rows with the <application>psql</application> program: + disabling the per-row timing, using the <literal>TIMING OFF</literal> + option: <screen> -CREATE TABLE t AS SELECT * FROM generate_series(1,100000); -\timing -SELECT COUNT(*) FROM t; -EXPLAIN ANALYZE SELECT COUNT(*) FROM t; +CREATE TABLE t AS SELECT * FROM generate_series(1, 100000); +EXPLAIN (ANALYZE, TIMING OFF) SELECT COUNT(*) FROM t; +EXPLAIN (ANALYZE, TIMING ON) SELECT COUNT(*) FROM t; </screen> </para> <para> - The i7-860 system measured runs the count query in 9.8 ms while - the <command>EXPLAIN ANALYZE</command> version takes 16.6 ms, each - processing just over 100,000 rows. That 6.8 ms difference means the timing - overhead per row is 68 ns, about twice what pg_test_timing estimated it - would be. Even that relatively small amount of overhead is making the fully - timed count statement take almost 70% longer. On more substantial queries, - the timing overhead would be less problematic. + The i9-9880H system measured shows an execution time of 4.116 ms for the + <literal>TIMING OFF</literal> query, and 6.965 ms for the + <literal>TIMING ON</literal>, each processing 100,000 rows. + + That 2.849 ms difference means the timing overhead per row is 28 ns. As + <literal>TIMING ON</literal> measures timestamps twice per row returned by + an executor node, the overhead is very close to what pg_test_timing + estimated it would be. </para> </refsect2> @@ -157,28 +164,31 @@ EXPLAIN ANALYZE SELECT COUNT(*) FROM t; <screen><![CDATA[ # cat /sys/devices/system/clocksource/clocksource0/available_clocksource -tsc hpet acpi_pm +tsc acpi_pm # echo acpi_pm > /sys/devices/system/clocksource/clocksource0/current_clocksource # pg_test_timing -Per loop time including overhead: 722.92 ns +Testing timing overhead for 3 seconds. +Per loop time including overhead: 708.58 ns Histogram of timing durations: - < us % of total count - 1 27.84870 1155682 - 2 72.05956 2990371 - 4 0.07810 3241 - 8 0.01357 563 - 16 0.00007 3 + < ns % of total count + 1024 99.79796 4225270 + 2048 0.15560 6588 + 4096 0.00035 15 + 8192 0.01738 736 + 16384 0.01679 711 + 32768 0.01190 504 ]]></screen> </para> <para> In this configuration, the sample <command>EXPLAIN ANALYZE</command> above - takes 115.9 ms. That's 1061 ns of timing overhead, again a small multiple - of what's measured directly by this utility. That much timing overhead - means the actual query itself is only taking a tiny fraction of the - accounted for time, most of it is being consumed in overhead instead. In - this configuration, any <command>EXPLAIN ANALYZE</command> totals involving - many timed operations would be inflated significantly by timing overhead. + shows an execution time of 148.7 ms. That's 1392 ns of per-row timing + overhead. Taking the two timestamps per row into account, that's again + close to what pg_test_timing estimated. That much timing overhead means + the actual query itself is only taking a tiny fraction of the accounted for + time, most of it is being consumed in overhead instead. In this + configuration, any <command>EXPLAIN ANALYZE</command> totals involving many + timed operations would be inflated significantly by timing overhead. </para> <para> @@ -196,33 +206,6 @@ kern.timecounter.hardware: ACPI-fast -> TSC </screen> </para> - <para> - Other systems may only allow setting the time source on boot. On older - Linux systems the "clock" kernel setting is the only way to make this sort - of change. And even on some more recent ones, the only option you'll see - for a clock source is "jiffies". Jiffies are the older Linux software clock - implementation, which can have good resolution when it's backed by fast - enough timing hardware, as in this example: - -<screen><![CDATA[ -$ cat /sys/devices/system/clocksource/clocksource0/available_clocksource -jiffies -$ dmesg | grep time.c -time.c: Using 3.579545 MHz WALL PM GTOD PIT/TSC timer. -time.c: Detected 2400.153 MHz processor. -$ pg_test_timing -Testing timing overhead for 3 seconds. -Per timing duration including loop overhead: 97.75 ns -Histogram of timing durations: - < us % of total count - 1 90.23734 27694571 - 2 9.75277 2993204 - 4 0.00981 3010 - 8 0.00007 22 - 16 0.00000 1 - 32 0.00000 1 -]]></screen></para> - </refsect2> <refsect2> -- 2.38.0 --2e47imhqa2hvpvyc-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ 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; 147+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 147+ messages in thread
end of thread, other threads:[~2025-10-20 05:29 UTC | newest] Thread overview: 147+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-04-04 00:24 [PATCH v3 3/3] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. Justin Pryzby <[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]> 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]> 2023-01-16 19:19 [PATCH v9 2/2] wip: report nanoseconds in pg_test_timing Andres Freund <[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 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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 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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 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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 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