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Be more realistic about plans involving Materialize nodes: take their

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cost into account while planning.
This commit is contained in:
Tom Lane
2002-11-30 05:21:03 +00:00
parent 829cedc8cf
commit 935969415a
19 changed files with 320 additions and 160 deletions
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44
src/backend/optimizer/util/pathnode.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.81 2002/11/30 00:08:20 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.82 2002/11/30 05:21:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -16,6 +16,7 @@
#include <math.h>
#include "executor/executor.h"
#include "nodes/plannodes.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
@ -450,6 +451,7 @@ create_result_path(RelOptInfo *rel, Path *subpath, List *constantqual)
pathnode->subpath = subpath;
pathnode->constantqual = constantqual;
/* Ideally should define cost_result(), but I'm too lazy */
if (subpath)
{
pathnode->path.startup_cost = subpath->startup_cost;
@ -464,6 +466,31 @@ create_result_path(RelOptInfo *rel, Path *subpath, List *constantqual)
return pathnode;
}
/*
* create_material_path
* Creates a path corresponding to a Material plan, returning the
* pathnode.
*/
MaterialPath *
create_material_path(RelOptInfo *rel, Path *subpath)
{
MaterialPath *pathnode = makeNode(MaterialPath);
pathnode->path.pathtype = T_Material;
pathnode->path.parent = rel;
pathnode->path.pathkeys = subpath->pathkeys;
pathnode->subpath = subpath;
cost_material(&pathnode->path,
subpath->total_cost,
rel->rows,
rel->width);
return pathnode;
}
/*
* create_subqueryscan_path
* Creates a path corresponding to a sequential scan of a subquery,
@ -583,6 +610,21 @@ create_mergejoin_path(Query *root,
if (innersortkeys &&
pathkeys_contained_in(innersortkeys, inner_path->pathkeys))
innersortkeys = NIL;
/*
* If we are not sorting the inner path, we may need a materialize
* node to ensure it can be marked/restored. (Sort does support
* mark/restore, so no materialize is needed in that case.)
*
* Since the inner side must be ordered, and only Sorts and IndexScans
* can create order to begin with, you might think there's no problem
* --- but you'd be wrong. Nestloop and merge joins can *preserve*
* the order of their inputs, so they can be selected as the input of
* a mergejoin, and they don't support mark/restore at present.
*/
if (innersortkeys == NIL &&
!ExecSupportsMarkRestore(inner_path->pathtype))
inner_path = (Path *)
create_material_path(inner_path->parent, inner_path);
pathnode->jpath.path.pathtype = T_MergeJoin;
pathnode->jpath.path.parent = joinrel;