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Arrange to free planning memory (or most of it, anyway) at completion

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of planning.  This should reduce memory requirements for large joins.
This commit is contained in:
Tom Lane 2000-07-27 04:51:04 +00:00
parent c7793a731c
commit 1cffbfcb56
1 changed files with 50 additions and 5 deletions
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55
src/backend/optimizer/plan/planmain.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.56 2000/07/24 03:11:01 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.57 2000/07/27 04:51:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -28,6 +28,7 @@
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "utils/memutils.h"
static Plan *subplanner(Query *root, List *flat_tlist, List *qual,
@ -176,6 +177,9 @@ subplanner(Query *root,
double tuple_fraction)
{
RelOptInfo *final_rel;
Plan *resultplan;
MemoryContext mycontext;
MemoryContext oldcxt;
Path *cheapestpath;
Path *presortedpath;
@ -212,6 +216,24 @@ subplanner(Query *root,
*/
root->query_pathkeys = canonicalize_pathkeys(root, root->query_pathkeys);
/*
* We might allocate quite a lot of storage during planning (due to
* constructing lots of Paths), but all of it can be reclaimed after
* we generate the finished Plan tree. Work in a temporary context
* to let that happen. We make the context a child of
* TransactionCommandContext so it will be freed if error abort.
*
* Note: beware of trying to move this up to the start of this routine.
* Some of the data structures built above --- notably the pathkey
* equivalence sets --- will still be needed after this routine exits.
*/
mycontext = AllocSetContextCreate(TransactionCommandContext,
"Planner",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(mycontext);
/*
* Ready to do the primary planning.
*/
@ -235,7 +257,9 @@ subplanner(Query *root,
root->query_pathkeys = NIL; /* signal unordered result */
/* Make childless Result node to evaluate given tlist. */
return (Plan *) make_result(flat_tlist, (Node *) qual, (Plan *) NULL);
resultplan = (Plan *) make_result(flat_tlist, (Node *) qual,
(Plan *) NULL);
goto plan_built;
}
#ifdef NOT_USED /* fix xfunc */
@ -295,7 +319,8 @@ subplanner(Query *root,
cheapestpath->pathkeys))
{
root->query_pathkeys = cheapestpath->pathkeys;
return create_plan(root, cheapestpath);
resultplan = create_plan(root, cheapestpath);
goto plan_built;
}
/*
@ -321,7 +346,8 @@ subplanner(Query *root,
{
/* Presorted path is cheaper, use it */
root->query_pathkeys = presortedpath->pathkeys;
return create_plan(root, presortedpath);
resultplan = create_plan(root, presortedpath);
goto plan_built;
}
/* otherwise, doing it the hard way is still cheaper */
}
@ -334,5 +360,24 @@ subplanner(Query *root,
* as an aggregate function...)
*/
root->query_pathkeys = cheapestpath->pathkeys;
return create_plan(root, cheapestpath);
resultplan = create_plan(root, cheapestpath);
plan_built:
/*
* Must copy the completed plan tree and its pathkeys out of temporary
* context.
*/
MemoryContextSwitchTo(oldcxt);
resultplan = copyObject(resultplan);
root->query_pathkeys = copyObject(root->query_pathkeys);
/*
* Now we can release the Path storage.
*/
MemoryContextDelete(mycontext);
return resultplan;
}