nodeGroup.c File Reference

#include "postgres.h"
#include "executor/executor.h"
#include "executor/nodeGroup.h"
#include "miscadmin.h"

Include dependency graph for nodeGroup.c:

Go to the source code of this file.

Functions
static TupleTableSlot *	ExecGroup (PlanState *pstate)
GroupState *	ExecInitGroup (Group *node, EState *estate, int eflags)
void	ExecEndGroup (GroupState *node)
void	ExecReScanGroup (GroupState *node)

Function Documentation

ExecEndGroup()

void ExecEndGroup

(

GroupState *

node

)

Definition at line 226 of file nodeGroup.c.

{
    PlanState  *outerPlan;
 
    outerPlan = outerPlanState(node);
    ExecEndNode(outerPlan);
}

References ExecEndNode(), outerPlan, and outerPlanState.

Referenced by ExecEndNode().

ExecGroup()

static TupleTableSlot * ExecGroup ( PlanState *  pstate )

static

Definition at line 36 of file nodeGroup.c.

{
    GroupState *node = castNode(GroupState, pstate);
    ExprContext *econtext;
    TupleTableSlot *firsttupleslot;
    TupleTableSlot *outerslot;
 
    CHECK_FOR_INTERRUPTS();
 
    /*
     * get state info from node
     */
    if (node->grp_done)
        return NULL;
    econtext = node->ss.ps.ps_ExprContext;
 
    /*
     * The ScanTupleSlot holds the (copied) first tuple of each group.
     */
    firsttupleslot = node->ss.ss_ScanTupleSlot;
 
    /*
     * We need not call ResetExprContext here because ExecQualAndReset() will
     * reset the per-tuple memory context once per input tuple.
     */
 
    /*
     * If first time through, acquire first input tuple and determine whether
     * to return it or not.
     */
    if (TupIsNull(firsttupleslot))
    {
        outerslot = ExecProcNode(outerPlanState(node));
        if (TupIsNull(outerslot))
        {
            /* empty input, so return nothing */
            node->grp_done = true;
            return NULL;
        }
        /* Copy tuple into firsttupleslot */
        ExecCopySlot(firsttupleslot, outerslot);
 
        /*
         * Set it up as input for qual test and projection.  The expressions
         * will access the input tuple as varno OUTER.
         */
        econtext->ecxt_outertuple = firsttupleslot;
 
        /*
         * Check the qual (HAVING clause); if the group does not match, ignore
         * it and fall into scan loop.
         */
        if (ExecQual(node->ss.ps.qual, econtext))
        {
            /*
             * Form and return a projection tuple using the first input tuple.
             */
            return ExecProject(node->ss.ps.ps_ProjInfo);
        }
        else
            InstrCountFiltered1(node, 1);
    }
 
    /*
     * This loop iterates once per input tuple group.  At the head of the
     * loop, we have finished processing the first tuple of the group and now
     * need to scan over all the other group members.
     */
    for (;;)
    {
        /*
         * Scan over all remaining tuples that belong to this group
         */
        for (;;)
        {
            outerslot = ExecProcNode(outerPlanState(node));
            if (TupIsNull(outerslot))
            {
                /* no more groups, so we're done */
                node->grp_done = true;
                return NULL;
            }
 
            /*
             * Compare with first tuple and see if this tuple is of the same
             * group.  If so, ignore it and keep scanning.
             */
            econtext->ecxt_innertuple = firsttupleslot;
            econtext->ecxt_outertuple = outerslot;
            if (!ExecQualAndReset(node->eqfunction, econtext))
                break;
        }
 
        /*
         * We have the first tuple of the next input group.  See if we want to
         * return it.
         */
        /* Copy tuple, set up as input for qual test and projection */
        ExecCopySlot(firsttupleslot, outerslot);
        econtext->ecxt_outertuple = firsttupleslot;
 
        /*
         * Check the qual (HAVING clause); if the group does not match, ignore
         * it and loop back to scan the rest of the group.
         */
        if (ExecQual(node->ss.ps.qual, econtext))
        {
            /*
             * Form and return a projection tuple using the first input tuple.
             */
            return ExecProject(node->ss.ps.ps_ProjInfo);
        }
        else
            InstrCountFiltered1(node, 1);
    }
}

References castNode, CHECK_FOR_INTERRUPTS, ExprContext::ecxt_innertuple, ExprContext::ecxt_outertuple, GroupState::eqfunction, ExecCopySlot(), ExecProcNode(), ExecProject(), ExecQual(), ExecQualAndReset(), GroupState::grp_done, InstrCountFiltered1, outerPlanState, ScanState::ps, PlanState::ps_ExprContext, PlanState::ps_ProjInfo, PlanState::qual, GroupState::ss, ScanState::ss_ScanTupleSlot, and TupIsNull.

Referenced by ExecInitGroup().

ExecInitGroup()

GroupState * ExecInitGroup	(	Group *	node,
		EState *	estate,
		int	eflags
	)

Definition at line 161 of file nodeGroup.c.

{
    GroupState *grpstate;
    const TupleTableSlotOps *tts_ops;
 
    /* check for unsupported flags */
    Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
 
    /*
     * create state structure
     */
    grpstate = makeNode(GroupState);
    grpstate->ss.ps.plan = (Plan *) node;
    grpstate->ss.ps.state = estate;
    grpstate->ss.ps.ExecProcNode = ExecGroup;
    grpstate->grp_done = false;
 
    /*
     * create expression context
     */
    ExecAssignExprContext(estate, &grpstate->ss.ps);
 
    /*
     * initialize child nodes
     */
    outerPlanState(grpstate) = ExecInitNode(outerPlan(node), estate, eflags);
 
    /*
     * Initialize scan slot and type.
     */
    tts_ops = ExecGetResultSlotOps(outerPlanState(&grpstate->ss), NULL);
    ExecCreateScanSlotFromOuterPlan(estate, &grpstate->ss, tts_ops);
 
    /*
     * Initialize result slot, type and projection.
     */
    ExecInitResultTupleSlotTL(&grpstate->ss.ps, &TTSOpsVirtual);
    ExecAssignProjectionInfo(&grpstate->ss.ps, NULL);
 
    /*
     * initialize child expressions
     */
    grpstate->ss.ps.qual =
        ExecInitQual(node->plan.qual, (PlanState *) grpstate);
 
    /*
     * Precompute fmgr lookup data for inner loop
     */
    grpstate->eqfunction =
        execTuplesMatchPrepare(ExecGetResultType(outerPlanState(grpstate)),
                               node->numCols,
                               node->grpColIdx,
                               node->grpOperators,
                               node->grpCollations,
                               &grpstate->ss.ps);
 
    return grpstate;
}

References Assert(), GroupState::eqfunction, EXEC_FLAG_BACKWARD, EXEC_FLAG_MARK, ExecAssignExprContext(), ExecAssignProjectionInfo(), ExecCreateScanSlotFromOuterPlan(), ExecGetResultSlotOps(), ExecGetResultType(), ExecGroup(), ExecInitNode(), ExecInitQual(), ExecInitResultTupleSlotTL(), PlanState::ExecProcNode, execTuplesMatchPrepare(), GroupState::grp_done, makeNode, Group::numCols, outerPlan, outerPlanState, PlanState::plan, Group::plan, ScanState::ps, PlanState::qual, Plan::qual, GroupState::ss, PlanState::state, and TTSOpsVirtual.

Referenced by ExecInitNode().

ExecReScanGroup()

void ExecReScanGroup

(

GroupState *

node

)

Definition at line 235 of file nodeGroup.c.

{
    PlanState  *outerPlan = outerPlanState(node);
 
    node->grp_done = false;
    /* must clear first tuple */
    ExecClearTuple(node->ss.ss_ScanTupleSlot);
 
    /*
     * 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(), GroupState::grp_done, outerPlan, outerPlanState, GroupState::ss, and ScanState::ss_ScanTupleSlot.

Referenced by ExecReScan().