Function findPartialMatch

src/backend/executor/nodeSubplan.c:728–755

* findPartialMatch: does the hashtable contain an entry that is not * provably distinct from the tuple? * * We have to scan the whole hashtable; we can't usefully use hashkeys * to guide probing, since we might get partial matches on tuples with * hashkeys quite unrelated to what we'd get from the given tuple. * * Caller must provide the equality functions to use, since in cross-type * cas

 * cases these are different from the hashtable's internal functions.
 */
static bool
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
				 FmgrInfo *eqfunctions)
{
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	TupleHashIterator hashiter;
	TupleHashEntry entry;

	InitTupleHashIterator(hashtable, &hashiter);
	while ((entry = ScanTupleHashTable(hashtable, &hashiter)) != NULL)
	{
		CHECK_FOR_INTERRUPTS();

		ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
		if (!execTuplesUnequal(slot, hashtable->tableslot,
							   numCols, keyColIdx,
							   eqfunctions,
							   hashtable->tab_collations,
							   hashtable->tempcxt))
		{
			TermTupleHashIterator(&hashiter);
			return true;
		}
	}
	/* No TermTupleHashIterator call needed here */
	return false;
}

/*
 * slotAllNulls: is the slot completely NULL?