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Commit90451fe

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When dealing with OR-of-ANDs quals, extract multiple subclauses of an AND
to use with a multiple-key index. Formerly we would only extract clausesthat had to do with the first key of the index, which was correct butdidn't exploit the index fully.
1 parent6d54070 commit90451fe

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1 file changed

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‎src/backend/optimizer/path/indxpath.c

Lines changed: 54 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.88 2000/07/25 04:30:42 tgl Exp $
12+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.89 2000/07/26 23:46:22 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -40,9 +40,23 @@
4040
#include"utils/syscache.h"
4141

4242

43+
/*
44+
* DoneMatchingIndexKeys() - MACRO
45+
*
46+
* Determine whether we should continue matching index keys in a clause.
47+
* Depends on if there are more to match or if this is a functional index.
48+
* In the latter case we stop after the first match since the there can
49+
* be only key (i.e. the function's return value) and the attributes in
50+
* keys list represent the arguments to the function. -mer 3 Oct. 1991
51+
*/
52+
#defineDoneMatchingIndexKeys(indexkeys,index) \
53+
(indexkeys[0] == 0 || \
54+
(index->indproc != InvalidOid))
55+
4356
#defineis_indexable_operator(clause,opclass,relam,indexkey_on_left) \
4457
(indexable_operator(clause,opclass,relam,indexkey_on_left) != InvalidOid)
4558

59+
4660
staticvoidmatch_index_orclauses(RelOptInfo*rel,IndexOptInfo*index,
4761
List*restrictinfo_list);
4862
staticList*match_index_orclause(RelOptInfo*rel,IndexOptInfo*index,
@@ -354,10 +368,11 @@ match_index_orclause(RelOptInfo *rel,
354368
* index, or if it is an AND clause any of whose members is an opclause
355369
* that matches the index.
356370
*
357-
* We currently only look to match the first key of an index against
358-
* 'or' subclauses. There are cases where a later key of a multi-key
359-
* index could be used (if other top-level clauses match earlier keys
360-
* of the index), but our poor brains are hurting already...
371+
* For multi-key indexes, we only look for matches to the first key;
372+
* without such a match the index is useless. If the clause is an AND
373+
* then we may be able to extract additional subclauses to use with the
374+
* later indexkeys, but we need not worry about that until
375+
* extract_or_indexqual_conditions() is called (if it ever is).
361376
*/
362377
staticbool
363378
match_or_subclause_to_indexkey(RelOptInfo*rel,
@@ -404,19 +419,45 @@ extract_or_indexqual_conditions(RelOptInfo *rel,
404419
Expr*orsubclause)
405420
{
406421
List*quals=NIL;
407-
intindexkey=index->indexkeys[0];
408-
Oidopclass=index->classlist[0];
409422

410423
if (and_clause((Node*)orsubclause))
411424
{
412-
List*item;
425+
/*
426+
* Extract relevant sub-subclauses in indexkey order. This is just
427+
* like group_clauses_by_indexkey() except that the input and output
428+
* are lists of bare clauses, not of RestrictInfo nodes.
429+
*/
430+
int*indexkeys=index->indexkeys;
431+
Oid*classes=index->classlist;
413432

414-
foreach(item,orsubclause->args)
433+
do
415434
{
416-
if (match_clause_to_indexkey(rel,index,indexkey,opclass,
417-
lfirst(item), false))
418-
quals=lappend(quals,lfirst(item));
419-
}
435+
intcurIndxKey=indexkeys[0];
436+
OidcurClass=classes[0];
437+
List*clausegroup=NIL;
438+
List*item;
439+
440+
foreach(item,orsubclause->args)
441+
{
442+
if (match_clause_to_indexkey(rel,index,
443+
curIndxKey,curClass,
444+
lfirst(item), false))
445+
clausegroup=lappend(clausegroup,lfirst(item));
446+
}
447+
448+
/*
449+
* If no clauses match this key, we're done; we don't want to look
450+
* at keys to its right.
451+
*/
452+
if (clausegroup==NIL)
453+
break;
454+
455+
quals=nconc(quals,clausegroup);
456+
457+
indexkeys++;
458+
classes++;
459+
}while (!DoneMatchingIndexKeys(indexkeys,index));
460+
420461
if (quals==NIL)
421462
elog(ERROR,"extract_or_indexqual_conditions: no matching clause");
422463
}
@@ -435,19 +476,6 @@ extract_or_indexqual_conditions(RelOptInfo *rel,
435476
****************************************************************************/
436477

437478

438-
/*
439-
* DoneMatchingIndexKeys() - MACRO
440-
*
441-
* Determine whether we should continue matching index keys in a clause.
442-
* Depends on if there are more to match or if this is a functional index.
443-
* In the latter case we stop after the first match since the there can
444-
* be only key (i.e. the function's return value) and the attributes in
445-
* keys list represent the arguments to the function. -mer 3 Oct. 1991
446-
*/
447-
#defineDoneMatchingIndexKeys(indexkeys,index) \
448-
(indexkeys[0] == 0 || \
449-
(index->indproc != InvalidOid))
450-
451479
/*
452480
* group_clauses_by_indexkey
453481
* Generates a list of restriction clauses that can be used with an index.

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