* stuff - checking the qualification and projecting the tuple
* appropriately.
*
- * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/executor/execScan.c,v 1.24 2003/08/04 00:43:17 momjian Exp $
+ * src/backend/executor/execScan.c
*
*-------------------------------------------------------------------------
*/
#include "utils/memutils.h"
-static bool tlist_matches_tupdesc(List *tlist, Index varno, TupleDesc tupdesc);
+/*
+ * ExecScanFetch -- check interrupts & fetch next potential tuple
+ *
+ * This routine is concerned with substituting a test tuple if we are
+ * inside an EvalPlanQual recheck. If we aren't, just execute
+ * the access method's next-tuple routine.
+ */
+static inline TupleTableSlot *
+ExecScanFetch(ScanState *node,
+ ExecScanAccessMtd accessMtd,
+ ExecScanRecheckMtd recheckMtd)
+{
+ EState *estate = node->ps.state;
+
+ CHECK_FOR_INTERRUPTS();
+
+ if (estate->es_epqTupleSlot != 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)
+ {
+ TupleTableSlot *slot = node->ss_ScanTupleSlot;
+
+ /*
+ * 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.
+ */
+ if (!(*recheckMtd) (node, slot))
+ ExecClearTuple(slot); /* would not be returned by scan */
+ return slot;
+ }
+ else if (estate->es_epqTupleSlot[scanrelid - 1] != NULL)
+ {
+ TupleTableSlot *slot = node->ss_ScanTupleSlot;
+
+ /* Return empty slot if we already returned a tuple */
+ if (estate->es_epqScanDone[scanrelid - 1])
+ return ExecClearTuple(slot);
+ /* Else mark to remember that we shouldn't return more */
+ estate->es_epqScanDone[scanrelid - 1] = true;
+
+ slot = estate->es_epqTupleSlot[scanrelid - 1];
+
+ /* 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);
+}
/* ----------------------------------------------------------------
* ExecScan
*
* Scans the relation using the 'access method' indicated and
- * returns the next qualifying tuple in the direction specified
- * in the global variable ExecDirection.
- * The access method returns the next tuple and execScan() is
+ * returns the next qualifying tuple.
+ * The access method returns the next tuple and ExecScan() is
* responsible for checking the tuple returned against the qual-clause.
*
+ * A 'recheck method' must also be provided that can check an
+ * arbitrary tuple of the relation against any qual conditions
+ * that are implemented internal to the access method.
+ *
* Conditions:
* -- the "cursor" maintained by the AMI is positioned at the tuple
* returned previously.
* ----------------------------------------------------------------
*/
TupleTableSlot *
-ExecScan(ScanState * node,
- ExecScanAccessMtd accessMtd) /* function returning a tuple */
+ExecScan(ScanState *node,
+ ExecScanAccessMtd accessMtd, /* function returning a tuple */
+ ExecScanRecheckMtd recheckMtd)
{
- EState *estate;
ExprContext *econtext;
- List *qual;
+ ExprState *qual;
ProjectionInfo *projInfo;
- ExprDoneCond isDone;
- TupleTableSlot *resultSlot;
/*
* Fetch data from node
*/
- estate = node->ps.state;
- econtext = node->ps.ps_ExprContext;
qual = node->ps.qual;
projInfo = node->ps.ps_ProjInfo;
+ econtext = node->ps.ps_ExprContext;
+
+ /* interrupt checks are in ExecScanFetch */
/*
- * Check to see if we're still projecting out tuples from a previous
- * scan tuple (because there is a function-returning-set in the
- * projection expressions). If so, try to project another one.
+ * 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 (node->ps.ps_TupFromTlist)
+ if (!qual && !projInfo)
{
- Assert(projInfo); /* can't get here if not projecting */
- resultSlot = ExecProject(projInfo, &isDone);
- if (isDone == ExprMultipleResult)
- return resultSlot;
- /* Done with that source tuple... */
- node->ps.ps_TupFromTlist = false;
+ ResetExprContext(econtext);
+ return ExecScanFetch(node, accessMtd, recheckMtd);
}
/*
* Reset per-tuple memory context to free any expression evaluation
- * storage allocated in the previous tuple cycle. Note this can't
- * happen until we're done projecting out tuples from a scan tuple.
+ * storage allocated in the previous tuple cycle.
*/
ResetExprContext(econtext);
/*
- * get a tuple from the access method loop until we obtain a tuple
- * which passes the qualification.
+ * get a tuple from the access method. Loop until we obtain a tuple that
+ * passes the qualification.
*/
for (;;)
{
TupleTableSlot *slot;
- CHECK_FOR_INTERRUPTS();
-
- slot = (*accessMtd) (node);
+ 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 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 ExecStoreTuple(NULL,
- projInfo->pi_slot,
- InvalidBuffer,
- true);
+ return ExecClearTuple(projInfo->pi_state.resultslot);
else
return slot;
}
/*
* check that the current tuple satisfies the qual-clause
*
- * check for non-nil qual here to avoid a function call to ExecQual()
- * when the qual is nil ... saves only a few cycles, but they add
- * up ...
+ * 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 || ExecQual(qual, econtext, false))
+ 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 --- unless we find we can project no
- * tuples from this scan tuple, in which case continue
- * scan.
+ * Form a projection tuple, store it in the result tuple slot
+ * and return it.
*/
- resultSlot = ExecProject(projInfo, &isDone);
- if (isDone != ExprEndResult)
- {
- node->ps.ps_TupFromTlist = (isDone == ExprMultipleResult);
- return resultSlot;
- }
+ return ExecProject(projInfo);
}
else
{
return slot;
}
}
+ else
+ InstrCountFiltered1(node, 1);
/*
* Tuple fails qual, so free per-tuple memory and try again.
* the scan node, because the planner will preferentially generate a matching
* tlist.
*
- * ExecAssignScanType must have been called already.
+ * The scan slot's descriptor must have been set already.
*/
void
-ExecAssignScanProjectionInfo(ScanState * node)
+ExecAssignScanProjectionInfo(ScanState *node)
{
Scan *scan = (Scan *) node->ps.plan;
+ TupleDesc tupdesc = node->ss_ScanTupleSlot->tts_tupleDescriptor;
+
+ ExecConditionalAssignProjectionInfo(&node->ps, tupdesc, scan->scanrelid);
+}
+
+/*
+ * ExecAssignScanProjectionInfoWithVarno
+ * As above, but caller can specify varno expected in Vars in the tlist.
+ */
+void
+ExecAssignScanProjectionInfoWithVarno(ScanState *node, Index varno)
+{
+ TupleDesc tupdesc = node->ss_ScanTupleSlot->tts_tupleDescriptor;
- if (tlist_matches_tupdesc(scan->plan.targetlist,
- scan->scanrelid,
- node->ss_ScanTupleSlot->ttc_tupleDescriptor))
- node->ps.ps_ProjInfo = NULL;
- else
- ExecAssignProjectionInfo(&node->ps);
+ ExecConditionalAssignProjectionInfo(&node->ps, tupdesc, varno);
}
-static bool
-tlist_matches_tupdesc(List *tlist, Index varno, TupleDesc tupdesc)
+/*
+ * ExecScanReScan
+ *
+ * This must be called within the ReScan function of any plan node type
+ * that uses ExecScan().
+ */
+void
+ExecScanReScan(ScanState *node)
{
- int numattrs = tupdesc->natts;
- int attrno;
+ 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);
- for (attrno = 1; attrno <= numattrs; attrno++)
+ /* Rescan EvalPlanQual tuple if we're inside an EvalPlanQual recheck */
+ if (estate->es_epqScanDone != NULL)
{
- Form_pg_attribute att_tup = tupdesc->attrs[attrno - 1];
- Var *var;
-
- if (tlist == NIL)
- return false; /* tlist too short */
- var = (Var *) ((TargetEntry *) lfirst(tlist))->expr;
- if (!var || !IsA(var, Var))
- return false; /* tlist item not a Var */
- Assert(var->varno == varno);
- if (var->varattno != attrno)
- return false; /* out of order */
- Assert(var->vartype == att_tup->atttypid);
- Assert(var->vartypmod == att_tup->atttypmod);
- Assert(var->varlevelsup == 0);
-
- tlist = lnext(tlist);
- }
+ Index scanrelid = ((Scan *) node->ps.plan)->scanrelid;
+
+ if (scanrelid > 0)
+ estate->es_epqScanDone[scanrelid - 1] = false;
+ else
+ {
+ Bitmapset *relids;
+ int rtindex = -1;
- if (tlist)
- return false; /* tlist too long */
+ /*
+ * 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_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));
- return true;
+ while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
+ {
+ Assert(rtindex > 0);
+ estate->es_epqScanDone[rtindex - 1] = false;
+ }
+ }
+ }
}
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