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[PATCH 8/8] Ignore correlation for new BRIN opclasses 3+ messages / 3 participants [nested] [flat]
* [PATCH 8/8] Ignore correlation for new BRIN opclasses @ 2020-09-12 13:07 Tomas Vondra <[email protected]> 0 siblings, 0 replies; 3+ messages in thread From: Tomas Vondra @ 2020-09-12 13:07 UTC (permalink / raw) The new BRIN opclasses (bloom and minmax-multi) are less sensitive to poorly correlated data, so just assume the data is perfectly correlated during costing. Author: Tomas Vondra <[email protected]> Discussion: https://postgr.es/m/[email protected] --- src/backend/access/brin/brin_bloom.c | 1 + src/backend/access/brin/brin_minmax_multi.c | 1 + src/backend/utils/adt/selfuncs.c | 19 ++++++++++++++++++- src/include/access/brin_internal.h | 3 +++ 4 files changed, 23 insertions(+), 1 deletion(-) diff --git a/src/backend/access/brin/brin_bloom.c b/src/backend/access/brin/brin_bloom.c index ac5a5c249c..84d91ec0ce 100644 --- a/src/backend/access/brin/brin_bloom.c +++ b/src/backend/access/brin/brin_bloom.c @@ -703,6 +703,7 @@ brin_bloom_opcinfo(PG_FUNCTION_ARGS) result = palloc0(MAXALIGN(SizeofBrinOpcInfo(1)) + sizeof(BloomOpaque)); + result->oi_ignore_correlation = true; result->oi_nstored = 1; result->oi_regular_nulls = true; result->oi_opaque = (BloomOpaque *) diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c index f9a7ae6608..4f6262f241 100644 --- a/src/backend/access/brin/brin_minmax_multi.c +++ b/src/backend/access/brin/brin_minmax_multi.c @@ -1306,6 +1306,7 @@ brin_minmax_multi_opcinfo(PG_FUNCTION_ARGS) result = palloc0(MAXALIGN(SizeofBrinOpcInfo(1)) + sizeof(MinmaxMultiOpaque)); + result->oi_ignore_correlation = true; result->oi_nstored = 1; result->oi_regular_nulls = true; result->oi_opaque = (MinmaxMultiOpaque *) diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index d5e61664bc..d0cc145938 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -98,6 +98,7 @@ #include <math.h> #include "access/brin.h" +#include "access/brin_internal.h" #include "access/brin_page.h" #include "access/gin.h" #include "access/table.h" @@ -7352,7 +7353,8 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count, double minimalRanges; double estimatedRanges; double selec; - Relation indexRel; + Relation indexRel = NULL; + TupleDesc tupdesc = NULL; ListCell *l; VariableStatData vardata; @@ -7374,6 +7376,7 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count, */ indexRel = index_open(index->indexoid, NoLock); brinGetStats(indexRel, &statsData); + tupdesc = RelationGetDescr(indexRel); index_close(indexRel, NoLock); /* work out the actual number of ranges in the index */ @@ -7407,6 +7410,17 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count, { IndexClause *iclause = lfirst_node(IndexClause, l); AttrNumber attnum = index->indexkeys[iclause->indexcol]; + FmgrInfo *opcInfoFn; + BrinOpcInfo *opcInfo; + Form_pg_attribute attr = TupleDescAttr(tupdesc, iclause->indexcol); + bool ignore_correlation; + + opcInfoFn = index_getprocinfo(indexRel, iclause->indexcol + 1, BRIN_PROCNUM_OPCINFO); + + opcInfo = (BrinOpcInfo *) + DatumGetPointer(FunctionCall1(opcInfoFn, attr->atttypid)); + + ignore_correlation = opcInfo->oi_ignore_correlation; /* attempt to lookup stats in relation for this index column */ if (attnum != 0) @@ -7477,6 +7491,9 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count, if (sslot.nnumbers > 0) varCorrelation = Abs(sslot.numbers[0]); + if (ignore_correlation) + varCorrelation = 1.0; + if (varCorrelation > *indexCorrelation) *indexCorrelation = varCorrelation; diff --git a/src/include/access/brin_internal.h b/src/include/access/brin_internal.h index e7ce4d0209..901febe375 100644 --- a/src/include/access/brin_internal.h +++ b/src/include/access/brin_internal.h @@ -30,6 +30,9 @@ typedef struct BrinOpcInfo /* Regular processing of NULLs in BrinValues? */ bool oi_regular_nulls; + /* Ignore correlation during cost estimation */ + bool oi_ignore_correlation; + /* Opaque pointer for the opclass' private use */ void *oi_opaque; -- 2.26.2 --------------CF71AF65F7C337C37C24B045-- ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: [PATCH] pgbench: add multiconnect option @ 2022-03-15 20:29 Greg Stark <[email protected]> 0 siblings, 1 reply; 3+ messages in thread From: Greg Stark @ 2022-03-15 20:29 UTC (permalink / raw) To: Fabien COELHO <[email protected]>; +Cc: David Christensen <[email protected]>; Michael Paquier <[email protected]>; pgsql-hackers Hi guys, It looks like David sent a patch and Fabien sent a followup patch. But there hasn't been a whole lot of discussion or further patches. It sounds like there are some basic questions about what the right interface should be. Are there specific questions that would be helpful for moving forward? ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: [PATCH] pgbench: add multiconnect option @ 2022-03-16 09:28 Fabien COELHO <[email protected]> parent: Greg Stark <[email protected]> 0 siblings, 0 replies; 3+ messages in thread From: Fabien COELHO @ 2022-03-16 09:28 UTC (permalink / raw) To: Greg Stark <[email protected]>; +Cc: David Christensen <[email protected]>; Michael Paquier <[email protected]>; pgsql-hackers Hello Greg, > It looks like David sent a patch and Fabien sent a followup patch. But > there hasn't been a whole lot of discussion or further patches. > > It sounds like there are some basic questions about what the right > interface should be. Are there specific questions that would be > helpful for moving forward? Review the designs and patches and tell us what you think? Personnaly, I think that allowing multiple connections is a good thing, especially if the code impact is reduced, which is the case with the version I sent. Then for me the next step would be to have a reconnection on errors so as to implement a client-side failover policy that could help testing a server-failover performance impact. I have done that internally but it requires that "Pgbench Serialization and deadlock errors" to land, as it would just be another error that can be handled. -- Fabien. ^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2022-03-16 09:28 UTC | newest] Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-09-12 13:07 [PATCH 8/8] Ignore correlation for new BRIN opclasses Tomas Vondra <[email protected]> 2022-03-15 20:29 Re: [PATCH] pgbench: add multiconnect option Greg Stark <[email protected]> 2022-03-16 09:28 ` Re: [PATCH] pgbench: add multiconnect option Fabien COELHO <[email protected]>
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