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Simple constraint exclusion. For now, only child tables of inheritance

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scans are candidates for exclusion; this should be fixed eventually.
Simon Riggs, with some help from Tom Lane.
This commit is contained in:
Tom Lane
2005-07-23 21:05:48 +00:00
parent 9af9d674c6
commit d007a95055
14 changed files with 621 additions and 105 deletions
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27
src/backend/optimizer/plan/createplan.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.194 2005/07/15 22:02:51 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.195 2005/07/23 21:05:46 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -40,7 +40,7 @@ static List *build_relation_tlist(RelOptInfo *rel);
static bool use_physical_tlist(RelOptInfo *rel);
static void disuse_physical_tlist(Plan *plan, Path *path);
static Join *create_join_plan(PlannerInfo *root, JoinPath *best_path);
static Append *create_append_plan(PlannerInfo *root, AppendPath *best_path);
static Plan *create_append_plan(PlannerInfo *root, AppendPath *best_path);
static Result *create_result_plan(PlannerInfo *root, ResultPath *best_path);
static Material *create_material_plan(PlannerInfo *root, MaterialPath *best_path);
static Plan *create_unique_plan(PlannerInfo *root, UniquePath *best_path);
@ -435,7 +435,7 @@ create_join_plan(PlannerInfo *root, JoinPath *best_path)
*
* Returns a Plan node.
*/
static Append *
static Plan *
create_append_plan(PlannerInfo *root, AppendPath *best_path)
{
Append *plan;
@ -443,6 +443,25 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
List *subplans = NIL;
ListCell *subpaths;
/*
* It is possible for the subplans list to contain only one entry,
* or even no entries. Handle these cases specially.
*
* XXX ideally, if there's just one entry, we'd not bother to generate
* an Append node but just return the single child. At the moment this
* does not work because the varno of the child scan plan won't match
* the parent-rel Vars it'll be asked to emit.
*/
if (best_path->subpaths == NIL)
{
/* Generate a Result plan with constant-FALSE gating qual */
return (Plan *) make_result(tlist,
(Node *) list_make1(makeBoolConst(false,
false)),
NULL);
}
/* Normal case with multiple subpaths */
foreach(subpaths, best_path->subpaths)
{
Path *subpath = (Path *) lfirst(subpaths);
@ -452,7 +471,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
plan = make_append(subplans, false, tlist);
return plan;
return (Plan *) plan;
}
/*