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help / color / mirror / Atom feedFrom: Tomas Vondra <[email protected]>
Subject: [PATCH 8/8] Ignore correlation for new BRIN opclasses
Date: Sat, 12 Sep 2020 15:07:59 +0200
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
--------------556A1DC61262AF15641DB204--
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