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Tweak OpernameGetCandidates() to reduce palloc overhead --- profiling 

showed that for common operator names such as '=', the pallocs done by
this routine occupied a surprisingly large fraction of the total time
for the parser to process an operator.
This commit is contained in:
Tom Lane 2003-12-29 21:33:09 +00:00
parent 21b3c0e0ec
commit 07f9f4d413
1 changed files with 20 additions and 3 deletions
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23
src/backend/catalog/namespace.c
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@ -13,7 +13,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.60 2003/12/12 18:45:08 petere Exp $
* $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.61 2003/12/29 21:33:09 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -659,6 +659,8 @@ FuncCandidateList
OpernameGetCandidates(List *names, char oprkind)
{
FuncCandidateList resultList = NULL;
char *resultSpace = NULL;
int nextResult = 0;
char *schemaname;
char *opername;
Oid namespaceId;
@ -685,6 +687,20 @@ OpernameGetCandidates(List *names, char oprkind)
CStringGetDatum(opername),
0, 0, 0);
/*
* In typical scenarios, most if not all of the operators found by the
* catcache search will end up getting returned; and there can be quite
* a few, for common operator names such as '=' or '+'. To reduce the
* time spent in palloc, we allocate the result space as an array large
* enough to hold all the operators. The original coding of this routine
* did a separate palloc for each operator, but profiling revealed that
* the pallocs used an unreasonably large fraction of parsing time.
*/
#define SPACE_PER_OP MAXALIGN(sizeof(struct _FuncCandidateList) + sizeof(Oid))
if (catlist->n_members > 0)
resultSpace = palloc(catlist->n_members * SPACE_PER_OP);
for (i = 0; i < catlist->n_members; i++)
{
HeapTuple opertup = &catlist->members[i]->tuple;
@ -768,8 +784,9 @@ OpernameGetCandidates(List *names, char oprkind)
/*
* Okay to add it to result list
*/
newResult = (FuncCandidateList)
palloc(sizeof(struct _FuncCandidateList) + sizeof(Oid));
newResult = (FuncCandidateList) (resultSpace + nextResult);
nextResult += SPACE_PER_OP;
newResult->pathpos = pathpos;
newResult->oid = HeapTupleGetOid(opertup);
newResult->nargs = 2;