database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-11 20:28:21 +03:00
Code Activity

Arrange for hash join to skip scanning the outer relation if it detects

Browse Source 
that the inner one is completely empty.  Per recent discussion.  Also some
cosmetic cleanups in nearby code.
This commit is contained in:
Tom Lane
2004-09-22 19:13:52 +00:00
parent 5d9f5c20dd
commit 9fcbe2af11
3 changed files with 27 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
src/backend/executor/nodeHashjoin.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.65 2004/09/17 18:28:53 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.66 2004/09/22 19:13:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -127,6 +127,17 @@ ExecHashJoin(HashJoinState *node)
hashNode->hashtable = hashtable;
(void) ExecProcNode((PlanState *) hashNode);
/*
* If the inner relation is completely empty, and we're not doing
* an outer join, we can quit without scanning the outer relation.
*/
if (!hashtable->hashNonEmpty && node->js.jointype != JOIN_LEFT)
{
ExecHashTableDestroy(hashtable);
node->hj_HashTable = NULL;
return NULL;
}
/*
* Open temp files for outer batches, if needed. Note that file
* buffers are palloc'd in regular executor context.
@ -138,10 +149,8 @@ ExecHashJoin(HashJoinState *node)
}
/*
* Now get an outer tuple and probe into the hash table for matches
* run the hash join process
*/
outerTupleSlot = node->js.ps.ps_OuterTupleSlot;
for (;;)
{
/*
@ -226,7 +235,7 @@ ExecHashJoin(HashJoinState *node)
* Only the joinquals determine MatchedOuter status, but all
* quals must pass to actually return the tuple.
*/
if (ExecQual(joinqual, econtext, false))
if (joinqual == NIL || ExecQual(joinqual, econtext, false))
{
node->hj_MatchedOuter = true;