Function ExecReScanCteScan

src/backend/executor/nodeCtescan.c:319–352

---------------------------------------------------------------- * ExecReScanCteScan * * Rescans the relation. * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
void
ExecReScanCteScan(CteScanState *node)
{
	Tuplestorestate *tuplestorestate = node->leader->cte_table;

	if (node->ss.ps.ps_ResultTupleSlot)
		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);

	ExecScanReScan(&node->ss);

	/*
	 * Clear the tuplestore if a new scan of the underlying CTE is required.
	 * This implicitly resets all the tuplestore's read pointers.  Note that
	 * multiple CTE nodes might redundantly clear the tuplestore; that's OK,
	 * and not unduly expensive.  We'll stop taking this path as soon as
	 * somebody has attempted to read something from the underlying CTE
	 * (thereby causing its chgParam to be cleared).
	 */
	if (node->leader->cteplanstate->chgParam != NULL)
	{
		tuplestore_clear(tuplestorestate);
		node->leader->eof_cte = false;
	}
	else
	{
		/*
		 * Else, just rewind my own pointer.  Either the underlying CTE
		 * doesn't need a rescan (and we can re-read what's in the tuplestore
		 * now), or somebody else already took care of it.
		 */
		tuplestore_select_read_pointer(tuplestorestate, node->readptr);
		tuplestore_rescan(tuplestorestate);
	}
}