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Teach planner to convert simple UNION ALL subqueries into append relations,

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thereby sharing code with the inheritance case.  This puts the UNION-ALL-view
approach to partitioned tables on par with inheritance, so far as constraint
exclusion is concerned: it works either way.  (Still need to update the docs
to say so.)  The definition of "simple UNION ALL" is a little simpler than
I would like --- basically the union arms can only be SELECT * FROM foo
--- but it's good enough for partitioned-table cases.
This commit is contained in:
Tom Lane
2006-02-03 21:08:49 +00:00
parent a25b1decef
commit 8b109ebf14
10 changed files with 888 additions and 388 deletions
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80
src/backend/optimizer/path/allpaths.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.140 2006/01/31 21:39:23 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.141 2006/02/03 21:08:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -42,6 +42,8 @@ int geqo_threshold;
static void set_base_rel_pathlists(PlannerInfo *root);
static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte);
static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
@ -133,7 +135,6 @@ set_base_rel_pathlists(PlannerInfo *root)
for (rti = 1; rti < root->simple_rel_array_size; rti++)
{
RelOptInfo *rel = root->simple_rel_array[rti];
RangeTblEntry *rte;
/* there may be empty slots corresponding to non-baserel RTEs */
if (rel == NULL)
@ -145,33 +146,44 @@ set_base_rel_pathlists(PlannerInfo *root)
if (rel->reloptkind != RELOPT_BASEREL)
continue;
rte = rt_fetch(rti, root->parse->rtable);
set_rel_pathlist(root, rel, rti,
rt_fetch(rti, root->parse->rtable));
}
}
if (rte->inh)
{
/* It's an "append relation", process accordingly */
set_append_rel_pathlist(root, rel, rti, rte);
}
else if (rel->rtekind == RTE_SUBQUERY)
{
/* Subquery --- generate a separate plan for it */
set_subquery_pathlist(root, rel, rti, rte);
}
else if (rel->rtekind == RTE_FUNCTION)
{
/* RangeFunction --- generate a separate plan for it */
set_function_pathlist(root, rel, rte);
}
else
{
/* Plain relation */
set_plain_rel_pathlist(root, rel, rte);
}
/*
* set_rel_pathlist
* Build access paths for a base relation
*/
static void
set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte)
{
if (rte->inh)
{
/* It's an "append relation", process accordingly */
set_append_rel_pathlist(root, rel, rti, rte);
}
else if (rel->rtekind == RTE_SUBQUERY)
{
/* Subquery --- generate a separate plan for it */
set_subquery_pathlist(root, rel, rti, rte);
}
else if (rel->rtekind == RTE_FUNCTION)
{
/* RangeFunction --- generate a separate plan for it */
set_function_pathlist(root, rel, rte);
}
else
{
/* Plain relation */
Assert(rel->rtekind == RTE_RELATION);
set_plain_rel_pathlist(root, rel, rte);
}
#ifdef OPTIMIZER_DEBUG
debug_print_rel(root, rel);
debug_print_rel(root, rel);
#endif
}
}
/*
@ -181,9 +193,6 @@ set_base_rel_pathlists(PlannerInfo *root)
static void
set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
{
Assert(rel->rtekind == RTE_RELATION);
Assert(!rte->inh);
/* Mark rel with estimated output rows, width, etc */
set_baserel_size_estimates(root, rel);
@ -265,6 +274,7 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
int childRTindex;
RelOptInfo *childrel;
RangeTblEntry *childrte;
Path *childpath;
ListCell *parentvars;
ListCell *childvars;
@ -346,10 +356,20 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
/*
* Compute the child's access paths, and save the cheapest.
*
* It's possible that the child is itself an appendrel, in which
* case we can "cut out the middleman" and just add its child
* paths to our own list. (We don't try to do this earlier because
* we need to apply both levels of transformation to the quals.)
*/
set_plain_rel_pathlist(root, childrel, childrte);
set_rel_pathlist(root, childrel, childRTindex, childrte);
subpaths = lappend(subpaths, childrel->cheapest_total_path);
childpath = childrel->cheapest_total_path;
if (IsA(childpath, AppendPath))
subpaths = list_concat(subpaths,
((AppendPath *) childpath)->subpaths);
else
subpaths = lappend(subpaths, childpath);
/*
* Propagate size information from the child back to the parent. For