1 files changed, 201 insertions, 0 deletions
diff --git a/src/backend/executor/nodeNamedtuplestorescan.c b/src/backend/executor/nodeNamedtuplestorescan.c
new file mode 100644
index 0000000..c0d1069
--- /dev/null
+++ b/src/backend/executor/nodeNamedtuplestorescan.c
@@ -0,0 +1,201 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeNamedtuplestorescan.c
+ *	  routines to handle NamedTuplestoreScan nodes.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/executor/nodeNamedtuplestorescan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "executor/execdebug.h"
+#include "executor/nodeNamedtuplestorescan.h"
+#include "miscadmin.h"
+#include "utils/queryenvironment.h"
+
+static TupleTableSlot *NamedTuplestoreScanNext(NamedTuplestoreScanState *node);
+
+/* ----------------------------------------------------------------
+ *		NamedTuplestoreScanNext
+ *
+ *		This is a workhorse for ExecNamedTuplestoreScan
+ * ----------------------------------------------------------------
+ */
+static TupleTableSlot *
+NamedTuplestoreScanNext(NamedTuplestoreScanState *node)
+{
+	TupleTableSlot *slot;
+
+	/* We intentionally do not support backward scan. */
+	Assert(ScanDirectionIsForward(node->ss.ps.state->es_direction));
+
+	/*
+	 * Get the next tuple from tuplestore. Return NULL if no more tuples.
+	 */
+	slot = node->ss.ss_ScanTupleSlot;
+	tuplestore_select_read_pointer(node->relation, node->readptr);
+	(void) tuplestore_gettupleslot(node->relation, true, false, slot);
+	return slot;
+}
+
+/*
+ * NamedTuplestoreScanRecheck -- access method routine to recheck a tuple in
+ * EvalPlanQual
+ */
+static bool
+NamedTuplestoreScanRecheck(NamedTuplestoreScanState *node, TupleTableSlot *slot)
+{
+	/* nothing to check */
+	return true;
+}
+
+/* ----------------------------------------------------------------
+ *		ExecNamedTuplestoreScan(node)
+ *
+ *		Scans the CTE sequentially and returns the next qualifying tuple.
+ *		We call the ExecScan() routine and pass it the appropriate
+ *		access method functions.
+ * ----------------------------------------------------------------
+ */
+static TupleTableSlot *
+ExecNamedTuplestoreScan(PlanState *pstate)
+{
+	NamedTuplestoreScanState *node = castNode(NamedTuplestoreScanState, pstate);
+
+	return ExecScan(&node->ss,
+					(ExecScanAccessMtd) NamedTuplestoreScanNext,
+					(ExecScanRecheckMtd) NamedTuplestoreScanRecheck);
+}
+
+
+/* ----------------------------------------------------------------
+ *		ExecInitNamedTuplestoreScan
+ * ----------------------------------------------------------------
+ */
+NamedTuplestoreScanState *
+ExecInitNamedTuplestoreScan(NamedTuplestoreScan *node, EState *estate, int eflags)
+{
+	NamedTuplestoreScanState *scanstate;
+	EphemeralNamedRelation enr;
+
+	/* check for unsupported flags */
+	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
+
+	/*
+	 * NamedTuplestoreScan should not have any children.
+	 */
+	Assert(outerPlan(node) == NULL);
+	Assert(innerPlan(node) == NULL);
+
+	/*
+	 * create new NamedTuplestoreScanState for node
+	 */
+	scanstate = makeNode(NamedTuplestoreScanState);
+	scanstate->ss.ps.plan = (Plan *) node;
+	scanstate->ss.ps.state = estate;
+	scanstate->ss.ps.ExecProcNode = ExecNamedTuplestoreScan;
+
+	enr = get_ENR(estate->es_queryEnv, node->enrname);
+	if (!enr)
+		elog(ERROR, "executor could not find named tuplestore \"%s\"",
+			 node->enrname);
+
+	Assert(enr->reldata);
+	scanstate->relation = (Tuplestorestate *) enr->reldata;
+	scanstate->tupdesc = ENRMetadataGetTupDesc(&(enr->md));
+	scanstate->readptr =
+		tuplestore_alloc_read_pointer(scanstate->relation, EXEC_FLAG_REWIND);
+
+	/*
+	 * The new read pointer copies its position from read pointer 0, which
+	 * could be anywhere, so explicitly rewind it.
+	 */
+	tuplestore_select_read_pointer(scanstate->relation, scanstate->readptr);
+	tuplestore_rescan(scanstate->relation);
+
+	/*
+	 * XXX: Should we add a function to free that read pointer when done?
+	 *
+	 * This was attempted, but it did not improve performance or memory usage
+	 * in any tested cases.
+	 */
+
+	/*
+	 * Miscellaneous initialization
+	 *
+	 * create expression context for node
+	 */
+	ExecAssignExprContext(estate, &scanstate->ss.ps);
+
+	/*
+	 * The scan tuple type is specified for the tuplestore.
+	 */
+	ExecInitScanTupleSlot(estate, &scanstate->ss, scanstate->tupdesc,
+						  &TTSOpsMinimalTuple);
+
+	/*
+	 * Initialize result type and projection.
+	 */
+	ExecInitResultTypeTL(&scanstate->ss.ps);
+	ExecAssignScanProjectionInfo(&scanstate->ss);
+
+	/*
+	 * initialize child expressions
+	 */
+	scanstate->ss.ps.qual =
+		ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
+
+	return scanstate;
+}
+
+/* ----------------------------------------------------------------
+ *		ExecEndNamedTuplestoreScan
+ *
+ *		frees any storage allocated through C routines.
+ * ----------------------------------------------------------------
+ */
+void
+ExecEndNamedTuplestoreScan(NamedTuplestoreScanState *node)
+{
+	/*
+	 * Free exprcontext
+	 */
+	ExecFreeExprContext(&node->ss.ps);
+
+	/*
+	 * clean out the tuple table
+	 */
+	if (node->ss.ps.ps_ResultTupleSlot)
+		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+	ExecClearTuple(node->ss.ss_ScanTupleSlot);
+}
+
+/* ----------------------------------------------------------------
+ *		ExecReScanNamedTuplestoreScan
+ *
+ *		Rescans the relation.
+ * ----------------------------------------------------------------
+ */
+void
+ExecReScanNamedTuplestoreScan(NamedTuplestoreScanState *node)
+{
+	Tuplestorestate *tuplestorestate = node->relation;
+
+	if (node->ss.ps.ps_ResultTupleSlot)
+		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+
+	ExecScanReScan(&node->ss);
+
+	/*
+	 * Rewind my own pointer.
+	 */
+	tuplestore_select_read_pointer(tuplestorestate, node->readptr);
+	tuplestore_rescan(tuplestorestate);
+}