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

Include dependency graph for execScan.c:

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 271 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 284 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 157 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 35 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 298 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.