1 files changed, 225 insertions, 0 deletions
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
new file mode 100644
index 00000000000..7136a623015
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+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -0,0 +1,225 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeRecursiveunion.c
+ *	  routines to handle RecursiveUnion nodes.
+ *
+ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeRecursiveunion.c,v 1.1 2008/10/04 21:56:53 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "executor/execdebug.h"
+#include "executor/nodeRecursiveunion.h"
+#include "miscadmin.h"
+
+
+/* ----------------------------------------------------------------
+ *		ExecRecursiveUnion(node)
+ *
+ *		Scans the recursive query sequentially and returns the next
+ *      qualifying tuple.
+ *
+ * 1. evaluate non recursive term and assign the result to RT
+ *
+ * 2. execute recursive terms
+ *
+ * 2.1 WT := RT
+ * 2.2 while WT is not empty repeat 2.3 to 2.6. if WT is empty returns RT
+ * 2.3 replace the name of recursive term with WT
+ * 2.4 evaluate the recursive term and store into WT
+ * 2.5 append WT to RT
+ * 2.6 go back to 2.2
+ * ----------------------------------------------------------------
+ */
+TupleTableSlot *
+ExecRecursiveUnion(RecursiveUnionState *node)
+{
+	PlanState  *outerPlan = outerPlanState(node);
+	PlanState  *innerPlan = innerPlanState(node);
+	RecursiveUnion *plan = (RecursiveUnion *) node->ps.plan;
+	TupleTableSlot *slot;
+
+	/* 1. Evaluate non-recursive term */
+	if (!node->recursing)
+	{
+		slot = ExecProcNode(outerPlan);
+		if (!TupIsNull(slot))
+		{
+			tuplestore_puttupleslot(node->working_table, slot);
+			return slot;
+		}
+		node->recursing = true;
+	}
+
+retry:
+	/* 2. Execute recursive term */
+	slot = ExecProcNode(innerPlan);
+	if (TupIsNull(slot))
+	{
+		if (node->intermediate_empty)
+			return NULL;
+
+		/* done with old working table ... */
+		tuplestore_end(node->working_table);
+
+		/* intermediate table becomes working table */
+		node->working_table = node->intermediate_table;
+
+		/* create new empty intermediate table */
+		node->intermediate_table = tuplestore_begin_heap(false, false, work_mem);
+		node->intermediate_empty = true;
+
+		/* and reset the inner plan */
+		innerPlan->chgParam = bms_add_member(innerPlan->chgParam,
+											 plan->wtParam);
+		goto retry;
+	}
+ 	else
+ 	{
+ 		node->intermediate_empty = false;
+ 		tuplestore_puttupleslot(node->intermediate_table, slot);
+ 	}
+
+	return slot;
+}
+
+/* ----------------------------------------------------------------
+ *		ExecInitRecursiveUnionScan
+ * ----------------------------------------------------------------
+ */
+RecursiveUnionState *
+ExecInitRecursiveUnion(RecursiveUnion *node, EState *estate, int eflags)
+{
+	RecursiveUnionState *rustate;
+	ParamExecData *prmdata;
+
+	/* check for unsupported flags */
+	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
+
+	/*
+	 * create state structure
+	 */
+	rustate = makeNode(RecursiveUnionState);
+	rustate->ps.plan = (Plan *) node;
+	rustate->ps.state = estate;
+
+	/* initialize processing state */
+	rustate->recursing = false;
+	rustate->intermediate_empty = true;
+	rustate->working_table = tuplestore_begin_heap(false, false, work_mem);
+	rustate->intermediate_table = tuplestore_begin_heap(false, false, work_mem);
+
+	/*
+	 * Make the state structure available to descendant WorkTableScan nodes
+	 * via the Param slot reserved for it.
+	 */
+	prmdata = &(estate->es_param_exec_vals[node->wtParam]);
+	Assert(prmdata->execPlan == NULL);
+	prmdata->value = PointerGetDatum(rustate);
+	prmdata->isnull = false;
+
+	/*
+	 * Miscellaneous initialization
+	 *
+	 * RecursiveUnion plans don't have expression contexts because they never
+	 * call ExecQual or ExecProject.
+	 */
+	Assert(node->plan.qual == NIL);
+
+#define RECURSIVEUNION_NSLOTS 1
+
+	/*
+	 * RecursiveUnion nodes still have Result slots, which hold pointers to
+	 * tuples, so we have to initialize them.
+	 */
+	ExecInitResultTupleSlot(estate, &rustate->ps);
+
+	/*
+	 * Initialize result tuple type and projection info.  (Note: we have
+	 * to set up the result type before initializing child nodes, because
+	 * nodeWorktablescan.c expects it to be valid.)
+	 */
+	ExecAssignResultTypeFromTL(&rustate->ps);
+	rustate->ps.ps_ProjInfo = NULL;
+
+	/*
+	 * initialize child nodes
+	 */
+	outerPlanState(rustate) = ExecInitNode(outerPlan(node), estate, eflags);
+	innerPlanState(rustate) = ExecInitNode(innerPlan(node), estate, eflags);
+
+	return rustate;
+}
+
+int
+ExecCountSlotsRecursiveUnion(RecursiveUnion *node)
+{
+	return ExecCountSlotsNode(outerPlan(node)) +
+		ExecCountSlotsNode(innerPlan(node)) +
+		RECURSIVEUNION_NSLOTS;
+}
+
+/* ----------------------------------------------------------------
+ *		ExecEndRecursiveUnionScan
+ *
+ *		frees any storage allocated through C routines.
+ * ----------------------------------------------------------------
+ */
+void
+ExecEndRecursiveUnion(RecursiveUnionState *node)
+{
+	/* Release tuplestores */
+	tuplestore_end(node->working_table);
+	tuplestore_end(node->intermediate_table);
+
+	/*
+	 * clean out the upper tuple table
+	 */
+	ExecClearTuple(node->ps.ps_ResultTupleSlot);
+
+	/*
+	 * close down subplans
+	 */
+	ExecEndNode(outerPlanState(node));
+	ExecEndNode(innerPlanState(node));
+}
+
+/* ----------------------------------------------------------------
+ *		ExecRecursiveUnionReScan
+ *
+ *		Rescans the relation.
+ * ----------------------------------------------------------------
+ */
+void
+ExecRecursiveUnionReScan(RecursiveUnionState *node, ExprContext *exprCtxt)
+{
+	PlanState  *outerPlan = outerPlanState(node);
+	PlanState  *innerPlan = innerPlanState(node);
+	RecursiveUnion *plan = (RecursiveUnion *) node->ps.plan;
+
+	/*
+	 * Set recursive term's chgParam to tell it that we'll modify the
+	 * working table and therefore it has to rescan.
+	 */
+	innerPlan->chgParam = bms_add_member(innerPlan->chgParam, plan->wtParam);
+
+	/*
+	 * if chgParam of subnode is not null then plan will be re-scanned by
+	 * first ExecProcNode.  Because of above, we only have to do this to
+	 * the non-recursive term.
+	 */
+	if (outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan, exprCtxt);
+
+	/* reset processing state */
+	node->recursing = false;
+	node->intermediate_empty = true;
+	tuplestore_clear(node->working_table);
+	tuplestore_clear(node->intermediate_table);
+}