nodeUnique.c File Reference

#include "postgres.h"
#include "executor/executor.h"
#include "executor/nodeUnique.h"
#include "miscadmin.h"
#include "utils/memutils.h"

Include dependency graph for nodeUnique.c:

Go to the source code of this file.

Functions
static TupleTableSlot *	ExecUnique (PlanState *pstate)
UniqueState *	ExecInitUnique (Unique *node, EState *estate, int eflags)
void	ExecEndUnique (UniqueState *node)
void	ExecReScanUnique (UniqueState *node)

Function Documentation

ExecEndUnique()

void ExecEndUnique

(

UniqueState *

node

)

Definition at line 169 of file nodeUnique.c.

{
    /* clean up tuple table */
    ExecClearTuple(node->ps.ps_ResultTupleSlot);
 
    ExecFreeExprContext(&node->ps);
 
    ExecEndNode(outerPlanState(node));
}

References ExecClearTuple(), ExecEndNode(), ExecFreeExprContext(), outerPlanState, UniqueState::ps, and PlanState::ps_ResultTupleSlot.

Referenced by ExecEndNode().

ExecInitUnique()

UniqueState* ExecInitUnique	(	Unique *	node,
		EState *	estate,
		int	eflags
	)

Definition at line 115 of file nodeUnique.c.

{
    UniqueState *uniquestate;
 
    /* check for unsupported flags */
    Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
 
    /*
     * create state structure
     */
    uniquestate = makeNode(UniqueState);
    uniquestate->ps.plan = (Plan *) node;
    uniquestate->ps.state = estate;
    uniquestate->ps.ExecProcNode = ExecUnique;
 
    /*
     * create expression context
     */
    ExecAssignExprContext(estate, &uniquestate->ps);
 
    /*
     * then initialize outer plan
     */
    outerPlanState(uniquestate) = ExecInitNode(outerPlan(node), estate, eflags);
 
    /*
     * Initialize result slot and type. Unique nodes do no projections, so
     * initialize projection info for this node appropriately.
     */
    ExecInitResultTupleSlotTL(&uniquestate->ps, &TTSOpsMinimalTuple);
    uniquestate->ps.ps_ProjInfo = NULL;
 
    /*
     * Precompute fmgr lookup data for inner loop
     */
    uniquestate->eqfunction =
        execTuplesMatchPrepare(ExecGetResultType(outerPlanState(uniquestate)),
                               node->numCols,
                               node->uniqColIdx,
                               node->uniqOperators,
                               node->uniqCollations,
                               &uniquestate->ps);
 
    return uniquestate;
}

References Assert(), UniqueState::eqfunction, EXEC_FLAG_BACKWARD, EXEC_FLAG_MARK, ExecAssignExprContext(), ExecGetResultType(), ExecInitNode(), ExecInitResultTupleSlotTL(), PlanState::ExecProcNode, execTuplesMatchPrepare(), ExecUnique(), makeNode, Unique::numCols, outerPlan, outerPlanState, PlanState::plan, UniqueState::ps, PlanState::ps_ProjInfo, PlanState::state, and TTSOpsMinimalTuple.

Referenced by ExecInitNode().

ExecReScanUnique()

void ExecReScanUnique

(

UniqueState *

node

)

Definition at line 181 of file nodeUnique.c.

{
    PlanState  *outerPlan = outerPlanState(node);
 
    /* must clear result tuple so first input tuple is returned */
    ExecClearTuple(node->ps.ps_ResultTupleSlot);
 
    /*
     * if chgParam of subnode is not null then plan will be re-scanned by
     * first ExecProcNode.
     */
    if (outerPlan->chgParam == NULL)
        ExecReScan(outerPlan);
}

References ExecClearTuple(), ExecReScan(), outerPlan, outerPlanState, UniqueState::ps, and PlanState::ps_ResultTupleSlot.

Referenced by ExecReScan().

ExecUnique()

static TupleTableSlot* ExecUnique ( PlanState *  pstate )

static

Definition at line 47 of file nodeUnique.c.

{
    UniqueState *node = castNode(UniqueState, pstate);
    ExprContext *econtext = node->ps.ps_ExprContext;
    TupleTableSlot *resultTupleSlot;
    TupleTableSlot *slot;
    PlanState  *outerPlan;
 
    CHECK_FOR_INTERRUPTS();
 
    /*
     * get information from the node
     */
    outerPlan = outerPlanState(node);
    resultTupleSlot = node->ps.ps_ResultTupleSlot;
 
    /*
     * now loop, returning only non-duplicate tuples. We assume that the
     * tuples arrive in sorted order so we can detect duplicates easily. The
     * first tuple of each group is returned.
     */
    for (;;)
    {
        /*
         * fetch a tuple from the outer subplan
         */
        slot = ExecProcNode(outerPlan);
        if (TupIsNull(slot))
        {
            /* end of subplan, so we're done */
            ExecClearTuple(resultTupleSlot);
            return NULL;
        }
 
        /*
         * Always return the first tuple from the subplan.
         */
        if (TupIsNull(resultTupleSlot))
            break;
 
        /*
         * Else test if the new tuple and the previously returned tuple match.
         * If so then we loop back and fetch another new tuple from the
         * subplan.
         */
        econtext->ecxt_innertuple = slot;
        econtext->ecxt_outertuple = resultTupleSlot;
        if (!ExecQualAndReset(node->eqfunction, econtext))
            break;
    }
 
    /*
     * We have a new tuple different from the previous saved tuple (if any).
     * Save it and return it.  We must copy it because the source subplan
     * won't guarantee that this source tuple is still accessible after
     * fetching the next source tuple.
     */
    return ExecCopySlot(resultTupleSlot, slot);
}

References castNode, CHECK_FOR_INTERRUPTS, ExprContext::ecxt_innertuple, ExprContext::ecxt_outertuple, UniqueState::eqfunction, ExecClearTuple(), ExecCopySlot(), ExecProcNode(), ExecQualAndReset(), outerPlan, outerPlanState, UniqueState::ps, PlanState::ps_ExprContext, PlanState::ps_ResultTupleSlot, and TupIsNull.

Referenced by ExecInitUnique().