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/*-------------------------------------------------------------------------
*
* nodeSubqueryscan.c
* Support routines for scanning subqueries (subselects in rangetable).
*
* This is just enough different from sublinks (nodeSubplan.c) to mean that
* we need two sets of code. Ought to look at trying to unify the cases.
*
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeSubqueryscan.c,v 1.37 2007/02/27 01:11:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecSubqueryScan scans a subquery.
* ExecSubqueryNext retrieve next tuple in sequential order.
* ExecInitSubqueryScan creates and initializes a subqueryscan node.
* ExecEndSubqueryScan releases any storage allocated.
* ExecSubqueryReScan rescans the relation
*
*/
#include "postgres.h"
#include "executor/execdebug.h"
#include "executor/nodeSubqueryscan.h"
static TupleTableSlot *SubqueryNext(SubqueryScanState *node);
/* ----------------------------------------------------------------
* Scan Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* SubqueryNext
*
* This is a workhorse for ExecSubqueryScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
SubqueryNext(SubqueryScanState *node)
{
TupleTableSlot *slot;
/*
* We need not support EvalPlanQual here, since we are not scanning a real
* relation.
*/
/*
* Get the next tuple from the sub-query.
*/
slot = ExecProcNode(node->subplan);
/*
* We just overwrite our ScanTupleSlot with the subplan's result slot,
* rather than expending the cycles for ExecCopySlot().
*/
node->ss.ss_ScanTupleSlot = slot;
return slot;
}
/* ----------------------------------------------------------------
* ExecSubqueryScan(node)
*
* Scans the subquery sequentially and returns the next qualifying
* tuple.
* It calls the ExecScan() routine and passes it the access method
* which retrieve tuples sequentially.
*
*/
TupleTableSlot *
ExecSubqueryScan(SubqueryScanState *node)
{
/*
* use SubqueryNext as access method
*/
return ExecScan(&node->ss, (ExecScanAccessMtd) SubqueryNext);
}
/* ----------------------------------------------------------------
* ExecInitSubqueryScan
* ----------------------------------------------------------------
*/
SubqueryScanState *
ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
{
SubqueryScanState *subquerystate;
/* check for unsupported flags */
Assert(!(eflags & EXEC_FLAG_MARK));
/*
* SubqueryScan should not have any "normal" children. Also, if planner
* left anything in subrtable, it's fishy.
*/
Assert(outerPlan(node) == NULL);
Assert(innerPlan(node) == NULL);
Assert(node->subrtable == NIL);
/*
* create state structure
*/
subquerystate = makeNode(SubqueryScanState);
subquerystate->ss.ps.plan = (Plan *) node;
subquerystate->ss.ps.state = estate;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &subquerystate->ss.ps);
/*
* initialize child expressions
*/
subquerystate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) subquerystate);
subquerystate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) subquerystate);
#define SUBQUERYSCAN_NSLOTS 2
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &subquerystate->ss.ps);
ExecInitScanTupleSlot(estate, &subquerystate->ss);
/*
* initialize subquery
*/
subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
subquerystate->ss.ps.ps_TupFromTlist = false;
/*
* Initialize scan tuple type (needed by ExecAssignScanProjectionInfo)
*/
ExecAssignScanType(&subquerystate->ss,
ExecGetResultType(subquerystate->subplan));
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&subquerystate->ss.ps);
ExecAssignScanProjectionInfo(&subquerystate->ss);
return subquerystate;
}
int
ExecCountSlotsSubqueryScan(SubqueryScan *node)
{
Assert(outerPlan(node) == NULL);
Assert(innerPlan(node) == NULL);
return ExecCountSlotsNode(node->subplan) +
SUBQUERYSCAN_NSLOTS;
}
/* ----------------------------------------------------------------
* ExecEndSubqueryScan
*
* frees any storage allocated through C routines.
* ----------------------------------------------------------------
*/
void
ExecEndSubqueryScan(SubqueryScanState *node)
{
/*
* Free the exprcontext
*/
ExecFreeExprContext(&node->ss.ps);
/*
* clean out the upper tuple table
*/
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
node->ss.ss_ScanTupleSlot = NULL; /* not ours to clear */
/*
* close down subquery
*/
ExecEndNode(node->subplan);
}
/* ----------------------------------------------------------------
* ExecSubqueryReScan
*
* Rescans the relation.
* ----------------------------------------------------------------
*/
void
ExecSubqueryReScan(SubqueryScanState *node, ExprContext *exprCtxt)
{
EState *estate;
estate = node->ss.ps.state;
/*
* ExecReScan doesn't know about my subplan, so I have to do
* changed-parameter signaling myself. This is just as well, because the
* subplan has its own memory context in which its chgParam state lives.
*/
if (node->ss.ps.chgParam != NULL)
UpdateChangedParamSet(node->subplan, node->ss.ps.chgParam);
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (node->subplan->chgParam == NULL)
ExecReScan(node->subplan, NULL);
node->ss.ss_ScanTupleSlot = NULL;
node->ss.ps.ps_TupFromTlist = false;
}
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