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44d5be0e53
There are some unimplemented aspects: recursive queries must use UNION ALL (should allow UNION too), and we don't have SEARCH or CYCLE clauses. These might or might not get done for 8.4, but even without them it's a pretty useful feature. There are also a couple of small loose ends and definitional quibbles, which I'll send a memo about to pgsql-hackers shortly. But let's land the patch now so we can get on with other development. Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane
432 lines
11 KiB
C
432 lines
11 KiB
C
/*-------------------------------------------------------------------------
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*
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* execAmi.c
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* miscellaneous executor access method routines
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*
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/backend/executor/execAmi.c,v 1.99 2008/10/04 21:56:53 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "executor/execdebug.h"
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#include "executor/instrument.h"
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#include "executor/nodeAgg.h"
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#include "executor/nodeAppend.h"
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#include "executor/nodeBitmapAnd.h"
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#include "executor/nodeBitmapHeapscan.h"
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#include "executor/nodeBitmapIndexscan.h"
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#include "executor/nodeBitmapOr.h"
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#include "executor/nodeFunctionscan.h"
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#include "executor/nodeGroup.h"
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#include "executor/nodeGroup.h"
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#include "executor/nodeHash.h"
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#include "executor/nodeHashjoin.h"
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#include "executor/nodeIndexscan.h"
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#include "executor/nodeLimit.h"
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#include "executor/nodeMaterial.h"
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#include "executor/nodeMergejoin.h"
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#include "executor/nodeNestloop.h"
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#include "executor/nodeRecursiveunion.h"
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#include "executor/nodeResult.h"
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#include "executor/nodeSeqscan.h"
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#include "executor/nodeSetOp.h"
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#include "executor/nodeSort.h"
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#include "executor/nodeSubplan.h"
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#include "executor/nodeSubqueryscan.h"
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#include "executor/nodeTidscan.h"
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#include "executor/nodeUnique.h"
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#include "executor/nodeValuesscan.h"
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#include "executor/nodeCtescan.h"
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#include "executor/nodeWorktablescan.h"
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/*
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* ExecReScan
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* Reset a plan node so that its output can be re-scanned.
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*
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* Note that if the plan node has parameters that have changed value,
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* the output might be different from last time.
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*
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* The second parameter is currently only used to pass a NestLoop plan's
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* econtext down to its inner child plan, in case that is an indexscan that
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* needs access to variables of the current outer tuple. (The handling of
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* this parameter is currently pretty inconsistent: some callers pass NULL
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* and some pass down their parent's value; so don't rely on it in other
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* situations. It'd probably be better to remove the whole thing and use
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* the generalized parameter mechanism instead.)
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*/
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void
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ExecReScan(PlanState *node, ExprContext *exprCtxt)
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{
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/* If collecting timing stats, update them */
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if (node->instrument)
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InstrEndLoop(node->instrument);
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/*
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* If we have changed parameters, propagate that info.
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*
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* Note: ExecReScanSetParamPlan() can add bits to node->chgParam,
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* corresponding to the output param(s) that the InitPlan will update.
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* Since we make only one pass over the list, that means that an InitPlan
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* can depend on the output param(s) of a sibling InitPlan only if that
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* sibling appears earlier in the list. This is workable for now given
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* the limited ways in which one InitPlan could depend on another, but
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* eventually we might need to work harder (or else make the planner
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* enlarge the extParam/allParam sets to include the params of depended-on
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* InitPlans).
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*/
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if (node->chgParam != NULL)
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{
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ListCell *l;
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foreach(l, node->initPlan)
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{
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SubPlanState *sstate = (SubPlanState *) lfirst(l);
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PlanState *splan = sstate->planstate;
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if (splan->plan->extParam != NULL) /* don't care about child
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* local Params */
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UpdateChangedParamSet(splan, node->chgParam);
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if (splan->chgParam != NULL)
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ExecReScanSetParamPlan(sstate, node);
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}
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foreach(l, node->subPlan)
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{
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SubPlanState *sstate = (SubPlanState *) lfirst(l);
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PlanState *splan = sstate->planstate;
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if (splan->plan->extParam != NULL)
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UpdateChangedParamSet(splan, node->chgParam);
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}
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/* Well. Now set chgParam for left/right trees. */
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if (node->lefttree != NULL)
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UpdateChangedParamSet(node->lefttree, node->chgParam);
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if (node->righttree != NULL)
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UpdateChangedParamSet(node->righttree, node->chgParam);
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}
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/* Shut down any SRFs in the plan node's targetlist */
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if (node->ps_ExprContext)
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ReScanExprContext(node->ps_ExprContext);
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/* And do node-type-specific processing */
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switch (nodeTag(node))
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{
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case T_ResultState:
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ExecReScanResult((ResultState *) node, exprCtxt);
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break;
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case T_AppendState:
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ExecReScanAppend((AppendState *) node, exprCtxt);
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break;
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case T_RecursiveUnionState:
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ExecRecursiveUnionReScan((RecursiveUnionState *) node, exprCtxt);
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break;
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case T_BitmapAndState:
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ExecReScanBitmapAnd((BitmapAndState *) node, exprCtxt);
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break;
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case T_BitmapOrState:
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ExecReScanBitmapOr((BitmapOrState *) node, exprCtxt);
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break;
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case T_SeqScanState:
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ExecSeqReScan((SeqScanState *) node, exprCtxt);
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break;
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case T_IndexScanState:
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ExecIndexReScan((IndexScanState *) node, exprCtxt);
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break;
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case T_BitmapIndexScanState:
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ExecBitmapIndexReScan((BitmapIndexScanState *) node, exprCtxt);
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break;
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case T_BitmapHeapScanState:
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ExecBitmapHeapReScan((BitmapHeapScanState *) node, exprCtxt);
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break;
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case T_TidScanState:
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ExecTidReScan((TidScanState *) node, exprCtxt);
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break;
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case T_SubqueryScanState:
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ExecSubqueryReScan((SubqueryScanState *) node, exprCtxt);
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break;
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case T_FunctionScanState:
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ExecFunctionReScan((FunctionScanState *) node, exprCtxt);
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break;
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case T_ValuesScanState:
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ExecValuesReScan((ValuesScanState *) node, exprCtxt);
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break;
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case T_CteScanState:
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ExecCteScanReScan((CteScanState *) node, exprCtxt);
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break;
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case T_WorkTableScanState:
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ExecWorkTableScanReScan((WorkTableScanState *) node, exprCtxt);
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break;
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case T_NestLoopState:
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ExecReScanNestLoop((NestLoopState *) node, exprCtxt);
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break;
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case T_MergeJoinState:
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ExecReScanMergeJoin((MergeJoinState *) node, exprCtxt);
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break;
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case T_HashJoinState:
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ExecReScanHashJoin((HashJoinState *) node, exprCtxt);
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break;
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case T_MaterialState:
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ExecMaterialReScan((MaterialState *) node, exprCtxt);
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break;
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case T_SortState:
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ExecReScanSort((SortState *) node, exprCtxt);
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break;
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case T_GroupState:
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ExecReScanGroup((GroupState *) node, exprCtxt);
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break;
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case T_AggState:
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ExecReScanAgg((AggState *) node, exprCtxt);
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break;
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case T_UniqueState:
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ExecReScanUnique((UniqueState *) node, exprCtxt);
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break;
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case T_HashState:
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ExecReScanHash((HashState *) node, exprCtxt);
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break;
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case T_SetOpState:
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ExecReScanSetOp((SetOpState *) node, exprCtxt);
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break;
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case T_LimitState:
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ExecReScanLimit((LimitState *) node, exprCtxt);
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break;
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default:
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elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
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break;
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}
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if (node->chgParam != NULL)
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{
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bms_free(node->chgParam);
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node->chgParam = NULL;
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}
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}
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/*
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* ExecMarkPos
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*
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* Marks the current scan position.
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*/
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void
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ExecMarkPos(PlanState *node)
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{
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switch (nodeTag(node))
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{
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case T_SeqScanState:
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ExecSeqMarkPos((SeqScanState *) node);
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break;
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case T_IndexScanState:
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ExecIndexMarkPos((IndexScanState *) node);
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break;
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case T_TidScanState:
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ExecTidMarkPos((TidScanState *) node);
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break;
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case T_ValuesScanState:
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ExecValuesMarkPos((ValuesScanState *) node);
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break;
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case T_MaterialState:
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ExecMaterialMarkPos((MaterialState *) node);
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break;
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case T_SortState:
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ExecSortMarkPos((SortState *) node);
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break;
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case T_ResultState:
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ExecResultMarkPos((ResultState *) node);
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break;
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default:
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/* don't make hard error unless caller asks to restore... */
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elog(DEBUG2, "unrecognized node type: %d", (int) nodeTag(node));
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break;
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}
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}
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/*
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* ExecRestrPos
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*
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* restores the scan position previously saved with ExecMarkPos()
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*
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* NOTE: the semantics of this are that the first ExecProcNode following
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* the restore operation will yield the same tuple as the first one following
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* the mark operation. It is unspecified what happens to the plan node's
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* result TupleTableSlot. (In most cases the result slot is unchanged by
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* a restore, but the node may choose to clear it or to load it with the
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* restored-to tuple.) Hence the caller should discard any previously
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* returned TupleTableSlot after doing a restore.
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*/
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void
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ExecRestrPos(PlanState *node)
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{
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switch (nodeTag(node))
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{
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case T_SeqScanState:
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ExecSeqRestrPos((SeqScanState *) node);
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break;
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case T_IndexScanState:
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ExecIndexRestrPos((IndexScanState *) node);
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break;
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case T_TidScanState:
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ExecTidRestrPos((TidScanState *) node);
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break;
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case T_ValuesScanState:
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ExecValuesRestrPos((ValuesScanState *) node);
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break;
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case T_MaterialState:
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ExecMaterialRestrPos((MaterialState *) node);
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break;
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case T_SortState:
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ExecSortRestrPos((SortState *) node);
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break;
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case T_ResultState:
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ExecResultRestrPos((ResultState *) node);
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break;
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default:
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elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
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break;
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}
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}
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/*
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* ExecSupportsMarkRestore - does a plan type support mark/restore?
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*
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* XXX Ideally, all plan node types would support mark/restore, and this
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* wouldn't be needed. For now, this had better match the routines above.
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* But note the test is on Plan nodetype, not PlanState nodetype.
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*
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* (However, since the only present use of mark/restore is in mergejoin,
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* there is no need to support mark/restore in any plan type that is not
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* capable of generating ordered output. So the seqscan, tidscan,
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* and valuesscan support is actually useless code at present.)
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*/
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bool
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ExecSupportsMarkRestore(NodeTag plantype)
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{
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switch (plantype)
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{
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case T_SeqScan:
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case T_IndexScan:
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case T_TidScan:
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case T_ValuesScan:
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case T_Material:
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case T_Sort:
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return true;
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case T_Result:
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/*
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* T_Result only supports mark/restore if it has a child plan that
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* does, so we do not have enough information to give a really
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* correct answer. However, for current uses it's enough to
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* always say "false", because this routine is not asked about
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* gating Result plans, only base-case Results.
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*/
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return false;
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default:
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break;
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}
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return false;
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}
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/*
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* ExecSupportsBackwardScan - does a plan type support backwards scanning?
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*
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* Ideally, all plan types would support backwards scan, but that seems
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* unlikely to happen soon. In some cases, a plan node passes the backwards
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* scan down to its children, and so supports backwards scan only if its
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* children do. Therefore, this routine must be passed a complete plan tree.
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*/
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bool
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ExecSupportsBackwardScan(Plan *node)
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{
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if (node == NULL)
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return false;
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switch (nodeTag(node))
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{
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case T_Result:
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if (outerPlan(node) != NULL)
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return ExecSupportsBackwardScan(outerPlan(node));
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else
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return false;
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case T_Append:
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{
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ListCell *l;
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foreach(l, ((Append *) node)->appendplans)
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{
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if (!ExecSupportsBackwardScan((Plan *) lfirst(l)))
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return false;
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}
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return true;
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}
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case T_SeqScan:
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case T_IndexScan:
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case T_TidScan:
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case T_FunctionScan:
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case T_ValuesScan:
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case T_CteScan:
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case T_WorkTableScan:
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return true;
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case T_SubqueryScan:
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return ExecSupportsBackwardScan(((SubqueryScan *) node)->subplan);
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case T_Material:
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case T_Sort:
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return true;
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case T_Limit:
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return ExecSupportsBackwardScan(outerPlan(node));
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default:
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return false;
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}
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}
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