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Extend the ExecInitNode API so that plan nodes receive a set of flag

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bits indicating which optional capabilities can actually be exercised
at runtime.  This will allow Sort and Material nodes, and perhaps later
other nodes, to avoid unnecessary overhead in common cases.
This commit just adds the infrastructure and arranges to pass the correct
flag values down to plan nodes; none of the actual optimizations are here
yet.  I'm committing this separately in case anyone wants to measure the
added overhead.  (It should be negligible.)

Simon Riggs and Tom Lane
This commit is contained in:
Tom Lane
2006-02-28 04:10:28 +00:00
parent 7f4f42fa10
commit 2c0ef9777c
53 changed files with 336 additions and 174 deletions
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39
src/include/executor/executor.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/executor/executor.h,v 1.124 2006/01/12 21:48:53 tgl Exp $
* $PostgreSQL: pgsql/src/include/executor/executor.h,v 1.125 2006/02/28 04:10:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -17,6 +17,39 @@
#include "executor/execdesc.h"
/*
* The "eflags" argument to ExecutorStart and the various ExecInitNode
* routines is a bitwise OR of the following flag bits, which tell the
* called plan node what to expect. Note that the flags will get modified
* as they are passed down the plan tree, since an upper node may require
* functionality in its subnode not demanded of the plan as a whole
* (example: MergeJoin requires mark/restore capability in its inner input),
* or an upper node may shield its input from some functionality requirement
* (example: Materialize shields its input from needing to do backward scan).
*
* EXPLAIN_ONLY indicates that the plan tree is being initialized just so
* EXPLAIN can print it out; it will not be run. Hence, no side-effects
* of startup should occur (such as creating a SELECT INTO target table).
* However, error checks (such as permission checks) should be performed.
*
* REWIND indicates that the plan node should try to efficiently support
* rescans without parameter changes. (Nodes must support ExecReScan calls
* in any case, but if this flag was not given, they are at liberty to do it
* through complete recalculation. Note that a parameter change forces a
* full recalculation in any case.)
*
* BACKWARD indicates that the plan node must respect the es_direction flag.
* When this is not passed, the plan node will only be run forwards.
*
* MARK indicates that the plan node must support Mark/Restore calls.
* When this is not passed, no Mark/Restore will occur.
*/
#define EXEC_FLAG_EXPLAIN_ONLY 0x0001 /* EXPLAIN, no ANALYZE */
#define EXEC_FLAG_REWIND 0x0002 /* need efficient rescan */
#define EXEC_FLAG_BACKWARD 0x0004 /* need backward scan */
#define EXEC_FLAG_MARK 0x0008 /* need mark/restore */
/*
* ExecEvalExpr was formerly a function containing a switch statement;
* now it's just a macro invoking the function pointed to by an ExprState
@ -87,7 +120,7 @@ extern HeapTuple ExecRemoveJunk(JunkFilter *junkfilter, TupleTableSlot *slot);
/*
* prototypes from functions in execMain.c
*/
extern void ExecutorStart(QueryDesc *queryDesc, bool explainOnly);
extern void ExecutorStart(QueryDesc *queryDesc, int eflags);
extern TupleTableSlot *ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction, long count);
extern void ExecutorEnd(QueryDesc *queryDesc);
@ -103,7 +136,7 @@ extern TupleTableSlot *EvalPlanQual(EState *estate, Index rti,
/*
* prototypes from functions in execProcnode.c
*/
extern PlanState *ExecInitNode(Plan *node, EState *estate);
extern PlanState *ExecInitNode(Plan *node, EState *estate, int eflags);
extern TupleTableSlot *ExecProcNode(PlanState *node);
extern Node *MultiExecProcNode(PlanState *node);
extern int ExecCountSlotsNode(Plan *node);