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* [PATCH 9/9] 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 15a8258677..d2c4172f48 100644
--- a/src/backend/access/brin/brin_bloom.c
+++ b/src/backend/access/brin/brin_bloom.c
@@ -410,6 +410,7 @@ 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 02aa618b49..437efa8d31 100644
--- a/src/backend/access/brin/brin_minmax_multi.c
+++ b/src/backend/access/brin/brin_minmax_multi.c
@@ -1798,6 +1798,7 @@ 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 47ca4ddbb5..bf40f9ce32 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 fdaff42722..5fbf8cf9c7 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
--------------4B194FF8F3EA3786FF9EAE1F
Content-Type: text/x-patch; charset=UTF-8;
name="0008-Define-multi-minmax-oclasses-for-types-with-20210203.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename*0="0008-Define-multi-minmax-oclasses-for-types-with-20210203.pa";
filename*1="tch"
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Failures in constraints regression test, "read only 0 of 8192 bytes"
@ 2024-03-02 22:29 Tomas Vondra <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Tomas Vondra @ 2024-03-02 22:29 UTC (permalink / raw)
To: Thomas Munro <[email protected]>; PostgreSQL Hackers <[email protected]>
These are "my" animals (running at a local university). There's a couple
interesting details:
1) the animals run on the same machine (one with gcc, one with clang)
2) I did upgrade the OS and restarted the machine on 2024/02/26, i.e.
right before the failures started
These might be just coincidences, but maybe something got broken by the
upgrade ... OTOH it's weird it'd affect just HEAD and none of the other
branches, and on two difference compilers.
Just to be sure I removed the buildroot, in case there's something wrong
with ccache. It's a wild guess, but I don't have any other idea.
regards
On 3/2/24 22:39, Thomas Munro wrote:
> These two animals seem to have got mixed up about about the size of
> this relation in the same place:
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=avocet&dt=2024-02-28%2017%3A34%3A30
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=trilobite&dt=2024-03-01%2006%3A47%3A53
>
> +++ /home/buildfarm/trilobite/buildroot/HEAD/pgsql.build/src/test/regress/results/constraints.out
> 2024-03-01 08:22:11.624897033 +0100
> @@ -573,42 +573,38 @@
> UNIQUE (i) DEFERRABLE INITIALLY DEFERRED;
> BEGIN;
> INSERT INTO unique_tbl VALUES (1, 'five');
> +ERROR: could not read blocks 0..0 in file "base/16384/21437": read
> only 0 of 8192 bytes
>
> That error message changed slightly in my smgrreadv() commit a couple
> of months ago (it would have been "block 0" and now it's "blocks 0..0"
> because now we can read more than one block at a time) but I don't
> immediately see how anything at that low level could be responsible
> for this.
>
>
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
^ permalink raw reply [nested|flat] 2+ messages in thread
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2020-09-12 13:07 [PATCH 9/9] Ignore correlation for new BRIN opclasses Tomas Vondra <[email protected]>
2024-03-02 22:29 Re: Failures in constraints regression test, "read only 0 of 8192 bytes" Tomas Vondra <[email protected]>
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