diff options
Diffstat (limited to 'src/backend/executor/execScan.c')
| -rw-r--r-- | src/backend/executor/execScan.c | 96 |
1 files changed, 91 insertions, 5 deletions
diff --git a/src/backend/executor/execScan.c b/src/backend/executor/execScan.c index 32386accbbd..f7733569ef9 100644 --- a/src/backend/executor/execScan.c +++ b/src/backend/executor/execScan.c @@ -12,7 +12,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/execScan.c,v 1.46 2009/04/02 20:59:10 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/executor/execScan.c,v 1.47 2009/10/26 02:26:29 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -26,6 +26,62 @@ static bool tlist_matches_tupdesc(PlanState *ps, List *tlist, Index varno, TupleDesc tupdesc); +/* + * ExecScanFetch -- 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; + + if (estate->es_epqTuple != 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; + + Assert(scanrelid > 0); + if (estate->es_epqTupleSet[scanrelid - 1]) + { + 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; + + /* Return empty slot if we haven't got a test tuple */ + if (estate->es_epqTuple[scanrelid - 1] == NULL) + return ExecClearTuple(slot); + + /* Store test tuple in the plan node's scan slot */ + ExecStoreTuple(estate->es_epqTuple[scanrelid - 1], + slot, InvalidBuffer, false); + + /* Check if it meets the access-method conditions */ + if (!(*recheckMtd) (node, slot)) + 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 * @@ -35,6 +91,10 @@ static bool tlist_matches_tupdesc(PlanState *ps, List *tlist, Index varno, 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. @@ -46,7 +106,8 @@ static bool tlist_matches_tupdesc(PlanState *ps, List *tlist, Index varno, Tuple */ TupleTableSlot * ExecScan(ScanState *node, - ExecScanAccessMtd accessMtd) /* function returning a tuple */ + ExecScanAccessMtd accessMtd, /* function returning a tuple */ + ExecScanRecheckMtd recheckMtd) { ExprContext *econtext; List *qual; @@ -65,7 +126,7 @@ ExecScan(ScanState *node, * all the overhead and return the raw scan tuple. */ if (!qual && !projInfo) - return (*accessMtd) (node); + return ExecScanFetch(node, accessMtd, recheckMtd); /* * Check to see if we're still projecting out tuples from a previous scan @@ -91,7 +152,7 @@ ExecScan(ScanState *node, ResetExprContext(econtext); /* - * get a tuple from the access method loop until we obtain a tuple which + * get a tuple from the access method. Loop until we obtain a tuple that * passes the qualification. */ for (;;) @@ -100,7 +161,7 @@ ExecScan(ScanState *node, CHECK_FOR_INTERRUPTS(); - slot = (*accessMtd) (node); + slot = ExecScanFetch(node, accessMtd, recheckMtd); /* * if the slot returned by the accessMtd contains NULL, then it means @@ -249,3 +310,28 @@ tlist_matches_tupdesc(PlanState *ps, List *tlist, Index varno, TupleDesc tupdesc return true; } + +/* + * ExecScanReScan + * + * This must be called within the ReScan function of any plan node type + * that uses ExecScan(). + */ +void +ExecScanReScan(ScanState *node) +{ + EState *estate = node->ps.state; + + /* Stop projecting any tuples from SRFs in the targetlist */ + node->ps.ps_TupFromTlist = false; + + /* Rescan EvalPlanQual tuple if we're inside an EvalPlanQual recheck */ + if (estate->es_epqScanDone != NULL) + { + Index scanrelid = ((Scan *) node->ps.plan)->scanrelid; + + Assert(scanrelid > 0); + + estate->es_epqScanDone[scanrelid - 1] = false; + } +} |