Function ExecScanHashTableForUnmatched

src/backend/executor/nodeHash.c:2399–2463

* ExecScanHashTableForUnmatched * scan the hash table for unmatched inner tuples * * On success, the inner tuple is stored into hjstate->hj_CurTuple and * econtext->ecxt_innertuple, using hjstate->hj_HashTupleSlot as the slot * for the latter. */

 * for the latter.
 */
bool
ExecScanHashTableForUnmatched(HashJoinState *hjstate, ExprContext *econtext)
{
	HashJoinTable hashtable = hjstate->hj_HashTable;
	HashJoinTuple hashTuple = hjstate->hj_CurTuple;

	for (;;)
	{
		/*
		 * hj_CurTuple is the address of the tuple last returned from the
		 * current bucket, or NULL if it's time to start scanning a new
		 * bucket.
		 */
		if (hashTuple != NULL)
			hashTuple = hashTuple->next.unshared;
		else if (hjstate->hj_CurBucketNo < hashtable->nbuckets)
		{
			hashTuple = hashtable->buckets.unshared[hjstate->hj_CurBucketNo];
			hjstate->hj_CurBucketNo++;
		}
		else if (hjstate->hj_CurSkewBucketNo < hashtable->nSkewBuckets)
		{
			int			j = hashtable->skewBucketNums[hjstate->hj_CurSkewBucketNo];

			hashTuple = hashtable->skewBucket[j]->tuples;
			hjstate->hj_CurSkewBucketNo++;
		}
		else
			break;				/* finished all buckets */

		while (hashTuple != NULL)
		{
			if (!HeapTupleHeaderHasMatch(HJTUPLE_MINTUPLE(hashTuple)))
			{
				TupleTableSlot *inntuple;

				/* insert hashtable's tuple into exec slot */
				inntuple = ExecStoreMinimalTuple(HJTUPLE_MINTUPLE(hashTuple),
												 hjstate->hj_HashTupleSlot,
												 false);	/* do not pfree */
				econtext->ecxt_innertuple = inntuple;

				/*
				 * Reset temp memory each time; although this function doesn't
				 * do any qual eval, the caller will, so let's keep it
				 * parallel to ExecScanHashBucket.
				 */
				ResetExprContext(econtext);

				hjstate->hj_CurTuple = hashTuple;
				return true;
			}

			hashTuple = hashTuple->next.unshared;
		}

		/* allow this loop to be cancellable */
		CHECK_FOR_INTERRUPTS();