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

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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
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12
src/backend/executor/nodeHash.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.86 2004/08/29 04:12:31 momjian Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.87 2004/09/22 19:13:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -32,8 +32,8 @@
/* ----------------------------------------------------------------
* ExecHash
*
* build hash table for hashjoin, all do partitioning if more
* than one batches are required.
* build hash table for hashjoin, doing partitioning if more
* than one batch is required.
* ----------------------------------------------------------------
*/
TupleTableSlot *
@ -81,6 +81,7 @@ ExecHash(HashState *node)
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
hashtable->hashNonEmpty = true;
econtext->ecxt_innertuple = slot;
ExecHashTableInsert(hashtable, econtext, hashkeys);
ExecClearTuple(slot);
@ -189,7 +190,7 @@ ExecEndHash(HashState *node)
/* ----------------------------------------------------------------
* ExecHashTableCreate
*
* create a hashtable in shared memory for hashjoin.
* create an empty hashtable data structure for hashjoin.
* ----------------------------------------------------------------
*/
HashJoinTable
@ -226,12 +227,13 @@ ExecHashTableCreate(Hash *node, List *hashOperators)
* The hashtable control block is just palloc'd from the executor's
* per-query memory context.
*/
hashtable = (HashJoinTable) palloc(sizeof(HashTableData));
hashtable = (HashJoinTable) palloc(sizeof(HashJoinTableData));
hashtable->nbuckets = nbuckets;
hashtable->totalbuckets = totalbuckets;
hashtable->buckets = NULL;
hashtable->nbatch = nbatch;
hashtable->curbatch = 0;
hashtable->hashNonEmpty = false;
hashtable->innerBatchFile = NULL;
hashtable->outerBatchFile = NULL;
hashtable->innerBatchSize = NULL;