execScan.c File Reference

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

Include dependency graph for execScan.c:

Go to the source code of this file.

Functions
static TupleTableSlot *	ExecScanFetch (ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
TupleTableSlot *	ExecScan (ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
void	ExecAssignScanProjectionInfo (ScanState *node)
void	ExecAssignScanProjectionInfoWithVarno (ScanState *node, int varno)
void	ExecScanReScan (ScanState *node)

Function Documentation

ExecAssignScanProjectionInfo()

void ExecAssignScanProjectionInfo

(

ScanState *

node

)

Definition at line 270 of file execScan.c.

{
    Scan       *scan = (Scan *) node->ps.plan;
    TupleDesc   tupdesc = node->ss_ScanTupleSlot->tts_tupleDescriptor;
 
    ExecConditionalAssignProjectionInfo(&node->ps, tupdesc, scan->scanrelid);
}

References ExecConditionalAssignProjectionInfo(), PlanState::plan, ScanState::ps, Scan::scanrelid, ScanState::ss_ScanTupleSlot, and TupleTableSlot::tts_tupleDescriptor.

Referenced by ExecInitBitmapHeapScan(), ExecInitCteScan(), ExecInitFunctionScan(), ExecInitIndexScan(), ExecInitNamedTuplestoreScan(), ExecInitSampleScan(), ExecInitSeqScan(), ExecInitSubqueryScan(), ExecInitTableFuncScan(), ExecInitTidRangeScan(), ExecInitTidScan(), ExecInitValuesScan(), and ExecWorkTableScan().

ExecAssignScanProjectionInfoWithVarno()

void ExecAssignScanProjectionInfoWithVarno	(	ScanState *	node,
		int	varno
	)

Definition at line 283 of file execScan.c.

{
    TupleDesc   tupdesc = node->ss_ScanTupleSlot->tts_tupleDescriptor;
 
    ExecConditionalAssignProjectionInfo(&node->ps, tupdesc, varno);
}

References ExecConditionalAssignProjectionInfo(), ScanState::ps, ScanState::ss_ScanTupleSlot, and TupleTableSlot::tts_tupleDescriptor.

Referenced by ExecInitCustomScan(), ExecInitForeignScan(), and ExecInitIndexOnlyScan().

ExecScan()

TupleTableSlot* ExecScan	(	ScanState *	node,
		ExecScanAccessMtd	accessMtd,
		ExecScanRecheckMtd	recheckMtd
	)

Definition at line 156 of file execScan.c.

{
    ExprContext *econtext;
    ExprState  *qual;
    ProjectionInfo *projInfo;
 
    /*
     * Fetch data from node
     */
    qual = node->ps.qual;
    projInfo = node->ps.ps_ProjInfo;
    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, 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, 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, PlanState::ps_ProjInfo, PlanState::qual, ResetExprContext, ExprState::resultslot, and TupIsNull.

Referenced by ExecBitmapHeapScan(), ExecCteScan(), ExecForeignScan(), ExecFunctionScan(), ExecIndexOnlyScan(), ExecIndexScan(), ExecNamedTuplestoreScan(), ExecSampleScan(), ExecSeqScan(), ExecSubqueryScan(), ExecTableFuncScan(), ExecTidRangeScan(), ExecTidScan(), ExecValuesScan(), and ExecWorkTableScan().

ExecScanFetch()

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

inlinestatic

Definition at line 34 of file execScan.c.

{
    EState     *estate = node->ps.state;
 
    CHECK_FOR_INTERRUPTS();
 
    if (estate->es_epq_active != NULL)
    {
        EPQState   *epqstate = estate->es_epq_active;
 
        /*
         * 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.  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, CHECK_FOR_INTERRUPTS, EState::es_epq_active, EvalPlanQualFetchRowMark(), ExecClearTuple(), PlanState::plan, ScanState::ps, EPQState::relsubs_done, EPQState::relsubs_rowmark, EPQState::relsubs_slot, ScanState::ss_ScanTupleSlot, PlanState::state, and TupIsNull.

Referenced by ExecScan().

ExecScanReScan()

void ExecScanReScan

(

ScanState *

node

)

Definition at line 297 of file execScan.c.

{
    EState     *estate = node->ps.state;
 
    /*
     * We must clear the scan tuple so that observers (e.g., execCurrent.c)
     * can tell that this plan node is not positioned on a tuple.
     */
    ExecClearTuple(node->ss_ScanTupleSlot);
 
    /*
     * Rescan EvalPlanQual tuple(s) if we're inside an EvalPlanQual recheck.
     * But don't lose the "blocked" status of blocked target relations.
     */
    if (estate->es_epq_active != NULL)
    {
        EPQState   *epqstate = estate->es_epq_active;
        Index       scanrelid = ((Scan *) node->ps.plan)->scanrelid;
 
        if (scanrelid > 0)
            epqstate->relsubs_done[scanrelid - 1] =
                epqstate->relsubs_blocked[scanrelid - 1];
        else
        {
            Bitmapset  *relids;
            int         rtindex = -1;
 
            /*
             * If an FDW or custom scan provider has replaced the join with a
             * scan, there are multiple RTIs; reset the epqScanDone flag for
             * all of them.
             */
            if (IsA(node->ps.plan, ForeignScan))
                relids = ((ForeignScan *) node->ps.plan)->fs_base_relids;
            else if (IsA(node->ps.plan, CustomScan))
                relids = ((CustomScan *) node->ps.plan)->custom_relids;
            else
                elog(ERROR, "unexpected scan node: %d",
                     (int) nodeTag(node->ps.plan));
 
            while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
            {
                Assert(rtindex > 0);
                epqstate->relsubs_done[rtindex - 1] =
                    epqstate->relsubs_blocked[rtindex - 1];
            }
        }
    }
}

References Assert, bms_next_member(), elog, ERROR, EState::es_epq_active, ExecClearTuple(), IsA, nodeTag, PlanState::plan, ScanState::ps, EPQState::relsubs_blocked, EPQState::relsubs_done, ScanState::ss_ScanTupleSlot, and PlanState::state.

Referenced by ExecReScanBitmapHeapScan(), ExecReScanCteScan(), ExecReScanForeignScan(), ExecReScanFunctionScan(), ExecReScanIndexOnlyScan(), ExecReScanIndexScan(), ExecReScanNamedTuplestoreScan(), ExecReScanSampleScan(), ExecReScanSeqScan(), ExecReScanSubqueryScan(), ExecReScanTableFuncScan(), ExecReScanTidRangeScan(), ExecReScanTidScan(), ExecReScanValuesScan(), and ExecReScanWorkTableScan().