Function setop_retrieve_hash_table

src/backend/executor/nodeSetOp.c:424–471

* ExecSetOp for hashed case: phase 2, retrieving groups from hash table */

 * ExecSetOp for hashed case: phase 2, retrieving groups from hash table
 */
static TupleTableSlot *
setop_retrieve_hash_table(SetOpState *setopstate)
{
	TupleHashEntryData *entry;
	TupleTableSlot *resultTupleSlot;

	/*
	 * get state info from node
	 */
	resultTupleSlot = setopstate->ps.ps_ResultTupleSlot;

	/*
	 * We loop retrieving groups until we find one we should return
	 */
	while (!setopstate->setop_done)
	{
		CHECK_FOR_INTERRUPTS();

		/*
		 * Find the next entry in the hash table
		 */
		entry = ScanTupleHashTable(setopstate->hashtable, &setopstate->hashiter);
		if (entry == NULL)
		{
			/* No more entries in hashtable, so done */
			setopstate->setop_done = true;
			return NULL;
		}

		/*
		 * See if we should emit any copies of this tuple, and if so return
		 * the first copy.
		 */
		set_output_count(setopstate, (SetOpStatePerGroup) entry->additional);

		if (setopstate->numOutput > 0)
		{
			setopstate->numOutput--;
			return ExecStoreMinimalTuple(entry->firstTuple,
										 resultTupleSlot,
										 false);
		}
	}

	/* No more groups */
	ExecClearTuple(resultTupleSlot);
	return NULL;
}

/* ----------------------------------------------------------------
 *		ExecInitSetOp