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Clean up BeginCommand and related routines. BeginCommand and EndCommand

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are now both invoked once per received SQL command (raw parsetree) from
pg_exec_query_string.  BeginCommand is actually just an empty routine
at the moment --- all its former operations have been pushed into tuple
receiver setup routines in printtup.c.  This makes for a clean distinction
between BeginCommand/EndCommand (once per command) and the tuple receiver
setup/teardown routines (once per ExecutorRun call), whereas the old code
was quite ad hoc.  Along the way, clean up the calling conventions for
ExecutorRun a little bit.
This commit is contained in:
Tom Lane
2002-02-27 19:36:13 +00:00
parent e22c9c4475
commit 6779c55c22
15 changed files with 266 additions and 361 deletions
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102
src/backend/executor/execMain.c
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@ -19,7 +19,7 @@
* query plan and ExecutorEnd() should always be called at the end of
* execution of a plan.
*
* ExecutorRun accepts 'feature' and 'count' arguments that specify whether
* ExecutorRun accepts direction and count arguments that specify whether
* the plan is to be executed forwards, backwards, and for how many tuples.
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
@ -27,7 +27,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.149 2001/10/25 05:49:27 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.150 2002/02/27 19:34:48 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -88,7 +88,7 @@ static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
* query plan
*
* returns a TupleDesc which describes the attributes of the tuples to
* be returned by the query.
* be returned by the query. (Same value is saved in queryDesc)
*
* NB: the CurrentMemoryContext when this is called must be the context
* to be used as the per-query context for the query plan. ExecutorRun()
@ -137,6 +137,8 @@ ExecutorStart(QueryDesc *queryDesc, EState *estate)
queryDesc->plantree,
estate);
queryDesc->tupDesc = result;
return result;
}
@ -149,25 +151,23 @@ ExecutorStart(QueryDesc *queryDesc, EState *estate)
*
* ExecutorStart must have been called already.
*
* the different features supported are:
* EXEC_RUN: retrieve all tuples in the forward direction
* EXEC_FOR: retrieve 'count' number of tuples in the forward dir
* EXEC_BACK: retrieve 'count' number of tuples in the backward dir
* EXEC_RETONE: return one tuple but don't 'retrieve' it
* used in postquel function processing
* If direction is NoMovementScanDirection then nothing is done
* except to start up/shut down the destination. Otherwise,
* we retrieve up to 'count' tuples in the specified direction.
*
* Note: count = 0 is interpreted as "no limit".
*
* ----------------------------------------------------------------
*/
TupleTableSlot *
ExecutorRun(QueryDesc *queryDesc, EState *estate, int feature, long count)
ExecutorRun(QueryDesc *queryDesc, EState *estate,
ScanDirection direction, long count)
{
CmdType operation;
Plan *plan;
TupleTableSlot *result;
CommandDest dest;
DestReceiver *destfunc;
TupleTableSlot *result;
/*
* sanity checks
@ -181,69 +181,33 @@ ExecutorRun(QueryDesc *queryDesc, EState *estate, int feature, long count)
operation = queryDesc->operation;
plan = queryDesc->plantree;
dest = queryDesc->dest;
destfunc = DestToFunction(dest);
/*
* startup tuple receiver
*/
estate->es_processed = 0;
estate->es_lastoid = InvalidOid;
destfunc = DestToFunction(dest);
(*destfunc->setup) (destfunc, (int) operation,
queryDesc->portalName, queryDesc->tupDesc);
/*
* FIXME: the dest setup function ought to be handed the tuple desc
* for the tuples to be output, but I'm not quite sure how to get that
* info at this point. For now, passing NULL is OK because no
* existing dest setup function actually uses the pointer.
* run plan
*/
(*destfunc->setup) (destfunc, (TupleDesc) NULL);
switch (feature)
{
case EXEC_RUN:
result = ExecutePlan(estate,
plan,
operation,
count,
ForwardScanDirection,
destfunc);
break;
case EXEC_FOR:
result = ExecutePlan(estate,
plan,
operation,
count,
ForwardScanDirection,
destfunc);
break;
/*
* retrieve next n "backward" tuples
*/
case EXEC_BACK:
result = ExecutePlan(estate,
plan,
operation,
count,
BackwardScanDirection,
destfunc);
break;
/*
* return one tuple but don't "retrieve" it. (this is used by
* the rule manager..) -cim 9/14/89
*/
case EXEC_RETONE:
result = ExecutePlan(estate,
plan,
operation,
ONE_TUPLE,
ForwardScanDirection,
destfunc);
break;
default:
elog(DEBUG, "ExecutorRun: Unknown feature %d", feature);
result = NULL;
break;
}
if (direction == NoMovementScanDirection)
result = NULL;
else
result = ExecutePlan(estate,
plan,
operation,
count,
direction,
destfunc);
/*
* shutdown receiver
*/
(*destfunc->cleanup) (destfunc);
return result;
@ -916,7 +880,7 @@ EndPlan(Plan *plan, EState *estate)
*
* processes the query plan to retrieve 'numberTuples' tuples in the
* direction specified.
* Retrieves all tuples if tupleCount is 0
* Retrieves all tuples if numberTuples is 0
*
* result is either a slot containing the last tuple in the case
* of a RETRIEVE or NULL otherwise.