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TupleHashTable: store additional data along with tuple.

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Previously, the caller needed to allocate the memory and the
TupleHashTable would store a pointer to it. That wastes space for the
palloc overhead as well as the size of the pointer itself.

Now, the TupleHashTable relies on the caller to correctly specify the
additionalsize, and allocates that amount of space. The caller can
then request a pointer into that space.

Discussion: https://postgr.es/m/b9cbf0219a9859dc8d240311643ff4362fd9602c.camel@j-davis.com
Reviewed-by: Heikki Linnakangas
This commit is contained in:
Jeff Davis
2025-01-10 17:14:37 -08:00
parent 34c6e65242
commit e0ece2a981
6 changed files with 78 additions and 31 deletions
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17
src/backend/executor/nodeSetOp.c
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@@ -425,6 +425,7 @@ setop_fill_hash_table(SetOpState *setopstate)
{
TupleTableSlot *outerslot;
TupleHashEntryData *entry;
SetOpStatePerGroup pergroup;
bool isnew;
outerslot = ExecProcNode(outerPlan);
@@ -437,16 +438,16 @@ setop_fill_hash_table(SetOpState *setopstate)
outerslot,
&isnew, NULL);
pergroup = TupleHashEntryGetAdditional(entry);
/* If new tuple group, initialize counts to zero */
if (isnew)
{
entry->additional = (SetOpStatePerGroup)
MemoryContextAllocZero(setopstate->hashtable->tablecxt,
sizeof(SetOpStatePerGroupData));
pergroup->numLeft = 0;
pergroup->numRight = 0;
}
/* Advance the counts */
((SetOpStatePerGroup) entry->additional)->numLeft++;
pergroup->numLeft++;
/* Must reset expression context after each hashtable lookup */
ResetExprContext(econtext);
@@ -478,7 +479,7 @@ setop_fill_hash_table(SetOpState *setopstate)
/* Advance the counts if entry is already present */
if (entry)
((SetOpStatePerGroup) entry->additional)->numRight++;
((SetOpStatePerGroup) TupleHashEntryGetAdditional(entry))->numRight++;
/* Must reset expression context after each hashtable lookup */
ResetExprContext(econtext);
@@ -496,7 +497,7 @@ setop_fill_hash_table(SetOpState *setopstate)
static TupleTableSlot *
setop_retrieve_hash_table(SetOpState *setopstate)
{
TupleHashEntryData *entry;
TupleHashEntry entry;
TupleTableSlot *resultTupleSlot;
/*
@@ -526,12 +527,12 @@ setop_retrieve_hash_table(SetOpState *setopstate)
* See if we should emit any copies of this tuple, and if so return
* the first copy.
*/
set_output_count(setopstate, (SetOpStatePerGroup) entry->additional);
set_output_count(setopstate, (SetOpStatePerGroup) TupleHashEntryGetAdditional(entry));
if (setopstate->numOutput > 0)
{
setopstate->numOutput--;
return ExecStoreMinimalTuple(entry->firstTuple,
return ExecStoreMinimalTuple(TupleHashEntryGetTuple(entry),
resultTupleSlot,
false);
}