Function ExecScanReScan

src/backend/executor/execScan.c:313–357

* ExecScanReScan * * This must be called within the ReScan function of any plan node type * that uses ExecScan(). */

 * that uses ExecScan().
 */
void
ExecScanReScan(ScanState *node)
{
	EState	   *estate = node->ps.state;

	/*
	 * We must clear the scan tuple so that observers (e.g., execCurrent.c)
	 * can tell that this plan node is not positioned on a tuple.
	 */
	ExecClearTuple(node->ss_ScanTupleSlot);

	/* Rescan EvalPlanQual tuple if we're inside an EvalPlanQual recheck */
	if (estate->es_epq_active != NULL)
	{
		EPQState   *epqstate = estate->es_epq_active;
		Index		scanrelid = ((Scan *) node->ps.plan)->scanrelid;

		if (scanrelid > 0)
			epqstate->relsubs_done[scanrelid - 1] = false;
		else
		{
			Bitmapset  *relids;
			int			rtindex = -1;

			/*
			 * If an FDW or custom scan provider has replaced the join with a
			 * scan, there are multiple RTIs; reset the epqScanDone flag for
			 * all of them.
			 */
			if (IsA(node->ps.plan, ForeignScan))
				relids = ((ForeignScan *) node->ps.plan)->fs_relids;
			else if (IsA(node->ps.plan, CustomScan))
				relids = ((CustomScan *) node->ps.plan)->custom_relids;
			else
				elog(ERROR, "unexpected scan node: %d",
					 (int) nodeTag(node->ps.plan));

			while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
			{
				Assert(rtindex > 0);
				epqstate->relsubs_done[rtindex - 1] = false;
			}
		}
	}
}