Function SeqNext

src/backend/executor/nodeSeqscan.c:57–124

---------------------------------------------------------------- * Scan Support * ---------------------------------------------------------------- */ ---------------------------------------------------------------- * SeqNext * * This is a workhorse for ExecSeqScan * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
static TupleTableSlot *
SeqNext(SeqScanState *node)
{
	TableScanDesc scandesc;
	EState	   *estate;
	ScanDirection direction;
	TupleTableSlot *slot;

	/*
	 * get information from the estate and scan state
	 */
	scandesc = node->ss.ss_currentScanDesc;
	estate = node->ss.ps.state;
	direction = estate->es_direction;
	slot = node->ss.ss_ScanTupleSlot;

	if (scandesc == NULL)
	{
		int nkeys = 0;
		ScanKey keys = NULL;

		/*
		 * Just when gp_enable_runtime_filter_pushdown enabled and
		 * node->filter_in_seqscan is false means scankey need to be pushed to
		 * AM.
		 */
		if (gp_enable_runtime_filter_pushdown && node->filter_in_seqscan && node->filters &&
			(table_scan_flags(node->ss.ss_currentRelation) &
			 (SCAN_SUPPORT_RUNTIME_FILTER)))
		{
			// pushdown runtime filter to AM
			keys = ScanKeyListToArray(node->filters, &nkeys);
		}

		/*
		 * We reach here if the scan is not parallel, or if we're serially
		 * executing a scan that was planned to be parallel.
		 */
		scandesc = table_beginscan_es(node->ss.ss_currentRelation,
									  estate->es_snapshot,
									  nkeys, keys,
									  NULL,
									  &node->ss.ps);
		node->ss.ss_currentScanDesc = scandesc;
	}

	/*
	 * get the next tuple from the table
	 */
	if (node->filter_in_seqscan && node->filters)
	{
		while (table_scan_getnextslot(scandesc, direction, slot))
		{
			// TODO: later pushdown bloom filter to AM
			if (!PassByBloomFilter(&node->ss.ps, node->filters, slot))
				continue;

			return slot;