Function TidRangeNext

src/backend/executor/nodeTidrangescan.c:215–263

---------------------------------------------------------------- * TidRangeNext * * Retrieve a tuple from the TidRangeScan node's currentRelation * using the TIDs in the TidRangeScanState information. * * ---------------------------------------------------------------- */

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

	/*
	 * extract necessary information from TID scan node
	 */
	scandesc = node->ss.ss_currentScanDesc;
	estate = node->ss.ps.state;
	slot = node->ss.ss_ScanTupleSlot;
	direction = estate->es_direction;

	if (!node->trss_inScan)
	{
		/* First time through, compute TID range to scan */
		if (!TidRangeEval(node))
			return NULL;

		if (scandesc == NULL)
		{
			scandesc = table_beginscan_tidrange(node->ss.ss_currentRelation,
												estate->es_snapshot,
												&node->trss_mintid,
												&node->trss_maxtid);
			node->ss.ss_currentScanDesc = scandesc;
		}
		else
		{
			/* rescan with the updated TID range */
			table_rescan_tidrange(scandesc, &node->trss_mintid,
								  &node->trss_maxtid);
		}

		node->trss_inScan = true;
	}

	/* Fetch the next tuple. */
	if (!table_scan_getnextslot_tidrange(scandesc, direction, slot))
	{
		node->trss_inScan = false;
		ExecClearTuple(slot);
	}

	return slot;
}

/*
 * TidRangeRecheck -- access method routine to recheck a tuple in EvalPlanQual