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[PATCH 8/8] Ignore correlation for new BRIN opclasses 2+ messages / 2 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; 2+ 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 c086e83236..22590b2351 100644 --- a/src/backend/access/brin/brin_bloom.c +++ b/src/backend/access/brin/brin_bloom.c @@ -412,6 +412,7 @@ 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 d2dc38adc8..6b1dd1040c 100644 --- a/src/backend/access/brin/brin_minmax_multi.c +++ b/src/backend/access/brin/brin_minmax_multi.c @@ -1737,6 +1737,7 @@ 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 52314d3aa1..0320d128f6 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 89254b5766..063b703208 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 --------------82D677E9F94AC7574E460205-- ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Proposal for Prototype Implementation to Enhance C/C++ Interoperability in PostgreSQL @ 2023-05-07 15:18 Tom Lane <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2023-05-07 15:18 UTC (permalink / raw) To: =?utf-8?B?55uP5LiA?= <[email protected]>; +Cc: pgsql-hackers "=?utf-8?B?55uP5LiA?=" <[email protected]> writes: > The proposed implementation can significantly improve the interoperability between C and C++ code in PostgreSQL. It allows for seamless integration of C++ code with PostgreSQL, without the need for complex workarounds or modifications to the existing codebase. That'd be nice to have, certainly ... > I have submitted the implementation on [GitHub](https://github.com/postgres/postgres/commit/1a9a2790430f256d9d0cc371249e43769d93eb8e#diff-6b6034caa0...). I would appreciate it if you could review the implementation and provide feedback. ... but I think this patch has no hope of being adequately portable. It seems extremely specific to one particular C++ implementation (unless you can show that every single thing you've used here is in the C++ standard), and then for good measure you've thrown in a new dependency on pthreads. On top of that, doesn't this require us to move our minimum language requirement to C++-something? We just barely got done deciding C99 was okay to use. regards, tom lane ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2023-05-07 15:18 UTC | newest] Thread overview: 2+ 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]> 2023-05-07 15:18 Re: Proposal for Prototype Implementation to Enhance C/C++ Interoperability in PostgreSQL Tom Lane <[email protected]>
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