execScan.h File Reference

#include "miscadmin.h"
#include "executor/executor.h"
#include "nodes/execnodes.h"

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Functions
static pg_attribute_always_inline TupleTableSlot *	ExecScanFetch (ScanState *node, EPQState *epqstate, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
static pg_attribute_always_inline TupleTableSlot *	ExecScanExtended (ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd, EPQState *epqstate, ExprState *qual, ProjectionInfo *projInfo)

Function Documentation

ExecScanExtended()

static pg_attribute_always_inline TupleTableSlot * ExecScanExtended ( ScanState *  node, ExecScanAccessMtd  accessMtd, ExecScanRecheckMtd  recheckMtd, EPQState *  epqstate, ExprState *  qual, ProjectionInfo *  projInfo  )

static

Definition at line 160 of file execScan.h.

{
    ExprContext *econtext = node->ps.ps_ExprContext;
 
    /* interrupt checks are in ExecScanFetch */
 
    /*
     * If we have neither a qual to check nor a projection to do, just skip
     * all the overhead and return the raw scan tuple.
     */
    if (!qual && !projInfo)
    {
        ResetExprContext(econtext);
        return ExecScanFetch(node, epqstate, accessMtd, recheckMtd);
    }
 
    /*
     * Reset per-tuple memory context to free any expression evaluation
     * storage allocated in the previous tuple cycle.
     */
    ResetExprContext(econtext);
 
    /*
     * get a tuple from the access method.  Loop until we obtain a tuple that
     * passes the qualification.
     */
    for (;;)
    {
        TupleTableSlot *slot;
 
        slot = ExecScanFetch(node, epqstate, accessMtd, recheckMtd);
 
        /*
         * if the slot returned by the accessMtd contains NULL, then it means
         * there is nothing more to scan so we just return an empty slot,
         * being careful to use the projection result slot so it has correct
         * tupleDesc.
         */
        if (TupIsNull(slot))
        {
            if (projInfo)
                return ExecClearTuple(projInfo->pi_state.resultslot);
            else
                return slot;
        }
 
        /*
         * place the current tuple into the expr context
         */
        econtext->ecxt_scantuple = slot;
 
        /*
         * check that the current tuple satisfies the qual-clause
         *
         * check for non-null qual here to avoid a function call to ExecQual()
         * when the qual is null ... saves only a few cycles, but they add up
         * ...
         */
        if (qual == NULL || ExecQual(qual, econtext))
        {
            /*
             * Found a satisfactory scan tuple.
             */
            if (projInfo)
            {
                /*
                 * Form a projection tuple, store it in the result tuple slot
                 * and return it.
                 */
                return ExecProject(projInfo);
            }
            else
            {
                /*
                 * Here, we aren't projecting, so just return scan tuple.
                 */
                return slot;
            }
        }
        else
            InstrCountFiltered1(node, 1);
 
        /*
         * Tuple fails qual, so free per-tuple memory and try again.
         */
        ResetExprContext(econtext);
    }
}

References ExprContext::ecxt_scantuple, ExecClearTuple(), ExecProject(), ExecQual(), ExecScanFetch(), InstrCountFiltered1, ProjectionInfo::pi_state, ScanState::ps, PlanState::ps_ExprContext, ResetExprContext, ExprState::resultslot, and TupIsNull.

Referenced by ExecScan(), ExecSeqScan(), ExecSeqScanWithProject(), ExecSeqScanWithQual(), and ExecSeqScanWithQualProject().

ExecScanFetch()

static pg_attribute_always_inline TupleTableSlot * ExecScanFetch ( ScanState *  node, EPQState *  epqstate, ExecScanAccessMtd  accessMtd, ExecScanRecheckMtd  recheckMtd  )

static

Definition at line 32 of file execScan.h.

{
    CHECK_FOR_INTERRUPTS();
 
    if (epqstate != NULL)
    {
        /*
         * We are inside an EvalPlanQual recheck.  Return the test tuple if
         * one is available, after rechecking any access-method-specific
         * conditions.
         */
        Index       scanrelid = ((Scan *) node->ps.plan)->scanrelid;
 
        if (scanrelid == 0)
        {
            /*
             * This is a ForeignScan or CustomScan which has pushed down a
             * join to the remote side.  If it is a descendant node in the EPQ
             * recheck plan tree, run the recheck method function.  Otherwise,
             * run the access method function below.
             */
            if (bms_is_member(epqstate->epqParam, node->ps.plan->extParam))
            {
                /*
                 * The recheck method is responsible not only for rechecking
                 * the scan/join quals but also for storing the correct tuple
                 * in the slot.
                 */
 
                TupleTableSlot *slot = node->ss_ScanTupleSlot;
 
                if (!(*recheckMtd) (node, slot))
                    ExecClearTuple(slot);   /* would not be returned by scan */
                return slot;
            }
        }
        else if (epqstate->relsubs_done[scanrelid - 1])
        {
            /*
             * Return empty slot, as either there is no EPQ tuple for this rel
             * or we already returned it.
             */
 
            TupleTableSlot *slot = node->ss_ScanTupleSlot;
 
            return ExecClearTuple(slot);
        }
        else if (epqstate->relsubs_slot[scanrelid - 1] != NULL)
        {
            /*
             * Return replacement tuple provided by the EPQ caller.
             */
 
            TupleTableSlot *slot = epqstate->relsubs_slot[scanrelid - 1];
 
            Assert(epqstate->relsubs_rowmark[scanrelid - 1] == NULL);
 
            /* Mark to remember that we shouldn't return it again */
            epqstate->relsubs_done[scanrelid - 1] = true;
 
            /* Return empty slot if we haven't got a test tuple */
            if (TupIsNull(slot))
                return NULL;
 
            /* Check if it meets the access-method conditions */
            if (!(*recheckMtd) (node, slot))
                return ExecClearTuple(slot);    /* would not be returned by
                                                 * scan */
            return slot;
        }
        else if (epqstate->relsubs_rowmark[scanrelid - 1] != NULL)
        {
            /*
             * Fetch and return replacement tuple using a non-locking rowmark.
             */
 
            TupleTableSlot *slot = node->ss_ScanTupleSlot;
 
            /* Mark to remember that we shouldn't return more */
            epqstate->relsubs_done[scanrelid - 1] = true;
 
            if (!EvalPlanQualFetchRowMark(epqstate, scanrelid, slot))
                return NULL;
 
            /* Return empty slot if we haven't got a test tuple */
            if (TupIsNull(slot))
                return NULL;
 
            /* Check if it meets the access-method conditions */
            if (!(*recheckMtd) (node, slot))
                return ExecClearTuple(slot);    /* would not be returned by
                                                 * scan */
            return slot;
        }
    }
 
    /*
     * Run the node-type-specific access method function to get the next tuple
     */
    return (*accessMtd) (node);
}

References Assert(), bms_is_member(), CHECK_FOR_INTERRUPTS, EPQState::epqParam, EvalPlanQualFetchRowMark(), ExecClearTuple(), Plan::extParam, PlanState::plan, ScanState::ps, EPQState::relsubs_done, EPQState::relsubs_rowmark, EPQState::relsubs_slot, ScanState::ss_ScanTupleSlot, and TupIsNull.

Referenced by ExecScanExtended().