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Back off previous patch to skip projection step in scan plan nodes,

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in the case where the node immediately above the scan is a Hash, Sort,
or Material node.  In these cases it's better to do the projection
so that we don't store unneeded columns in the hash/sort/materialize
table.  Per discussion a few days ago with Anagh Lal.
This commit is contained in:
Tom Lane 2003-02-16 06:06:32 +00:00
parent 51972a9d5d
commit 72933a92c7
1 changed files with 42 additions and 1 deletions
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43
src/backend/optimizer/plan/createplan.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.136 2003/02/09 06:56:27 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.137 2003/02/16 06:06:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -35,6 +35,7 @@
static Scan *create_scan_plan(Query *root, Path *best_path);
static bool use_physical_tlist(RelOptInfo *rel);
static void disuse_physical_tlist(Plan *plan, Path *path);
static Join *create_join_plan(Query *root, JoinPath *best_path);
static Append *create_append_plan(Query *root, AppendPath *best_path);
static Result *create_result_plan(Query *root, ResultPath *best_path);
@ -310,6 +311,33 @@ use_physical_tlist(RelOptInfo *rel)
return true;
}
/*
* disuse_physical_tlist
* Switch a plan node back to emitting only Vars actually referenced.
*
* If the plan node immediately above a scan would prefer to get only
* needed Vars and not a physical tlist, it must call this routine to
* undo the decision made by use_physical_tlist(). Currently, Hash, Sort,
* and Material nodes want this, so they don't have to store useless columns.
*/
static void
disuse_physical_tlist(Plan *plan, Path *path)
{
/* Only need to undo it for path types handled by create_scan_plan() */
switch (path->pathtype)
{
case T_IndexScan:
case T_SeqScan:
case T_TidScan:
case T_SubqueryScan:
case T_FunctionScan:
plan->targetlist = path->parent->targetlist;
break;
default:
break;
}
}
/*
* create_join_plan
* Create a join plan for 'best_path' and (recursively) plans for its
@ -468,6 +496,9 @@ create_material_plan(Query *root, MaterialPath *best_path)
subplan = create_plan(root, best_path->subpath);
/* We don't want any excess columns in the materialized tuples */
disuse_physical_tlist(subplan, best_path->subpath);
plan = make_material(subplan->targetlist, subplan);
copy_path_costsize(&plan->plan, (Path *) best_path);
@ -906,20 +937,27 @@ create_mergejoin_plan(Query *root,
/*
* Create explicit sort nodes for the outer and inner join paths if
* necessary. The sort cost was already accounted for in the path.
* Make sure there are no excess columns in the inputs if sorting.
*/
if (best_path->outersortkeys)
{
disuse_physical_tlist(outer_plan, best_path->jpath.outerjoinpath);
outer_plan = (Plan *)
make_sort_from_pathkeys(root,
outer_plan,
best_path->jpath.outerjoinpath->parent->relids,
best_path->outersortkeys);
}
if (best_path->innersortkeys)
{
disuse_physical_tlist(inner_plan, best_path->jpath.innerjoinpath);
inner_plan = (Plan *)
make_sort_from_pathkeys(root,
inner_plan,
best_path->jpath.innerjoinpath->parent->relids,
best_path->innersortkeys);
}
/*
* Now we can build the mergejoin node.
@ -976,6 +1014,9 @@ create_hashjoin_plan(Query *root,
innerhashkeys = lappend(innerhashkeys, get_rightop(lfirst(hcl)));
}
/* We don't want any excess columns in the hashed tuples */
disuse_physical_tlist(inner_plan, best_path->jpath.innerjoinpath);
/*
* Build the hash node and hash join node.
*/