195 lines
5.1 KiB
C
195 lines
5.1 KiB
C
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/*-------------------------------------------------------------------------
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*
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* nodeWorktablescan.c
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* routines to handle WorkTableScan nodes.
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*
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/executor/nodeWorktablescan.c,v 1.1 2008/10/04 21:56:53 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "executor/execdebug.h"
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#include "executor/nodeWorktablescan.h"
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static TupleTableSlot *WorkTableScanNext(WorkTableScanState *node);
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/* ----------------------------------------------------------------
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* WorkTableScanNext
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*
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* This is a workhorse for ExecWorkTableScan
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* ----------------------------------------------------------------
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*/
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static TupleTableSlot *
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WorkTableScanNext(WorkTableScanState *node)
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{
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TupleTableSlot *slot;
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EState *estate;
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ScanDirection direction;
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Tuplestorestate *tuplestorestate;
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/*
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* get information from the estate and scan state
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*/
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estate = node->ss.ps.state;
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direction = estate->es_direction;
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tuplestorestate = node->rustate->working_table;
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/*
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* Get the next tuple from tuplestore. Return NULL if no more tuples.
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*/
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slot = node->ss.ss_ScanTupleSlot;
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(void) tuplestore_gettupleslot(tuplestorestate,
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ScanDirectionIsForward(direction),
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slot);
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return slot;
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}
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/* ----------------------------------------------------------------
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* ExecWorkTableScan(node)
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*
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* Scans the worktable sequentially and returns the next qualifying tuple.
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* It calls the ExecScan() routine and passes it the access method
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* which retrieves tuples sequentially.
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* ----------------------------------------------------------------
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*/
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TupleTableSlot *
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ExecWorkTableScan(WorkTableScanState *node)
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{
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/*
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* use WorkTableScanNext as access method
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*/
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return ExecScan(&node->ss, (ExecScanAccessMtd) WorkTableScanNext);
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}
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/* ----------------------------------------------------------------
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* ExecInitWorkTableScan
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* ----------------------------------------------------------------
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*/
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WorkTableScanState *
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ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
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{
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WorkTableScanState *scanstate;
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ParamExecData *prmdata;
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/* check for unsupported flags */
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Assert(!(eflags & EXEC_FLAG_MARK));
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/*
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* WorkTableScan should not have any children.
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*/
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Assert(outerPlan(node) == NULL);
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Assert(innerPlan(node) == NULL);
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/*
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* create new WorkTableScanState for node
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*/
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scanstate = makeNode(WorkTableScanState);
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scanstate->ss.ps.plan = (Plan *) node;
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scanstate->ss.ps.state = estate;
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/*
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* Find the ancestor RecursiveUnion's state
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* via the Param slot reserved for it.
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*/
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prmdata = &(estate->es_param_exec_vals[node->wtParam]);
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Assert(prmdata->execPlan == NULL);
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Assert(!prmdata->isnull);
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scanstate->rustate = (RecursiveUnionState *) DatumGetPointer(prmdata->value);
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Assert(scanstate->rustate && IsA(scanstate->rustate, RecursiveUnionState));
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/*
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* Miscellaneous initialization
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*
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* create expression context for node
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*/
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ExecAssignExprContext(estate, &scanstate->ss.ps);
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/*
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* initialize child expressions
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*/
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scanstate->ss.ps.targetlist = (List *)
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ExecInitExpr((Expr *) node->scan.plan.targetlist,
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(PlanState *) scanstate);
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scanstate->ss.ps.qual = (List *)
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ExecInitExpr((Expr *) node->scan.plan.qual,
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(PlanState *) scanstate);
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#define WORKTABLESCAN_NSLOTS 2
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/*
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* tuple table initialization
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*/
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ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
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ExecInitScanTupleSlot(estate, &scanstate->ss);
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/*
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* The scan tuple type (ie, the rowtype we expect to find in the work
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* table) is the same as the result rowtype of the ancestor RecursiveUnion
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* node. Note this depends on the assumption that RecursiveUnion doesn't
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* allow projection.
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*/
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ExecAssignScanType(&scanstate->ss,
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ExecGetResultType(&scanstate->rustate->ps));
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/*
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* Initialize result tuple type and projection info.
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*/
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ExecAssignResultTypeFromTL(&scanstate->ss.ps);
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ExecAssignScanProjectionInfo(&scanstate->ss);
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scanstate->ss.ps.ps_TupFromTlist = false;
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return scanstate;
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}
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int
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ExecCountSlotsWorkTableScan(WorkTableScan *node)
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{
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return ExecCountSlotsNode(outerPlan(node)) +
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ExecCountSlotsNode(innerPlan(node)) +
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WORKTABLESCAN_NSLOTS;
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}
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/* ----------------------------------------------------------------
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* ExecEndWorkTableScan
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*
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* frees any storage allocated through C routines.
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* ----------------------------------------------------------------
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*/
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void
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ExecEndWorkTableScan(WorkTableScanState *node)
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{
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/*
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* Free exprcontext
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*/
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ExecFreeExprContext(&node->ss.ps);
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/*
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* clean out the tuple table
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*/
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ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
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ExecClearTuple(node->ss.ss_ScanTupleSlot);
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}
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/* ----------------------------------------------------------------
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* ExecWorkTableScanReScan
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*
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* Rescans the relation.
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* ----------------------------------------------------------------
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*/
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void
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ExecWorkTableScanReScan(WorkTableScanState *node, ExprContext *exprCtxt)
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{
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ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
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tuplestore_rescan(node->rustate->working_table);
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}
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