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The original patch to avoid building a hash join's hashtable when the

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outer relation is empty did not work, per test case from Patrick Welche.
It tried to use nodeHashjoin.c's high-level mechanisms for fetching an
outer-relation tuple, but that code expected the hash table to be filled
already.  As patched, the code failed in corner cases such as having no
outer-relation tuples for the first hash batch.  Revert and rewrite.
This commit is contained in:
Tom Lane
2005-09-25 19:37:35 +00:00
parent dd102d3683
commit e990b9ce23
3 changed files with 94 additions and 163 deletions
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52
src/backend/executor/nodeHash.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.94 2005/06/15 07:27:44 neilc Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.95 2005/09/25 19:37:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -37,22 +37,14 @@ static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
/* ----------------------------------------------------------------
* ExecHash
*
* produce the first tuple from our child node (and _only_ the
* first tuple). This is of limited general use -- it does not
* hash its output, and produces only a single tuple. It is
* provided so that hash join can probe the inner hash input to
* determine whether it is empty without needing to build the
* entire hash table first, which is what MultiExecHash() would
* do.
* stub for pro forma compliance
* ----------------------------------------------------------------
*/
TupleTableSlot *
ExecHash(HashState *node)
{
if (TupIsNull(node->firstTuple))
node->firstTuple = ExecProcNode(outerPlanState(node));
return node->firstTuple;
elog(ERROR, "Hash node does not support ExecProcNode call convention");
return NULL;
}
/* ----------------------------------------------------------------
@ -71,7 +63,6 @@ MultiExecHash(HashState *node)
TupleTableSlot *slot;
ExprContext *econtext;
uint32 hashvalue;
bool cleared_first_tuple = false;
/* must provide our own instrumentation support */
if (node->ps.instrument)
@ -94,19 +85,9 @@ MultiExecHash(HashState *node)
*/
for (;;)
{
/* use and clear the tuple produced by ExecHash(), if any */
if (!TupIsNull(node->firstTuple))
{
slot = node->firstTuple;
node->firstTuple = NULL;
cleared_first_tuple = true;
}
else
{
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
}
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
hashtable->totalTuples += 1;
/* We have to compute the hash value */
econtext->ecxt_innertuple = slot;
@ -116,19 +97,7 @@ MultiExecHash(HashState *node)
/* must provide our own instrumentation support */
if (node->ps.instrument)
{
/*
* XXX: kludge -- if ExecHash() was invoked, we've already
* included the tuple that it produced in the row output count
* for this node, so subtract 1 from the # of hashed tuples.
*/
if (cleared_first_tuple)
InstrStopNodeMulti(node->ps.instrument,
hashtable->totalTuples - 1);
else
InstrStopNodeMulti(node->ps.instrument,
hashtable->totalTuples);
}
InstrStopNodeMulti(node->ps.instrument, hashtable->totalTuples);
/*
* We do not return the hash table directly because it's not a subtype
@ -161,7 +130,6 @@ ExecInitHash(Hash *node, EState *estate)
hashstate->ps.state = estate;
hashstate->hashtable = NULL;
hashstate->hashkeys = NIL; /* will be set by parent HashJoin */
hashstate->firstTuple = NULL;
/*
* Miscellaneous initialization
@ -221,8 +189,6 @@ ExecEndHash(HashState *node)
{
PlanState *outerPlan;
node->firstTuple = NULL;
/*
* free exprcontext
*/
@ -864,8 +830,6 @@ ExecHashTableReset(HashJoinTable hashtable)
void
ExecReScanHash(HashState *node, ExprContext *exprCtxt)
{
node->firstTuple = NULL;
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.