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Repair two constraint-exclusion corner cases triggered by proving that an

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inheritance child of an UPDATE/DELETE target relation can be excluded by
constraints.  I had rearranged some code in set_append_rel_pathlist() to
avoid "useless" work when a child is excluded, but overdid it and left
the child with no cheapest_path entry, causing possible failure later
if the appendrel was involved in a join.  Also, it seems that the dummy
plan generated by inheritance_planner() when all branches are excluded
has to be a bit less dummy now than was required in 8.2.
Per report from Jan Wieck.  Add his test case to the regression tests.
This commit is contained in:
Tom Lane
2007-05-26 18:23:02 +00:00
parent 604ffd280b
commit cadb78330e
4 changed files with 134 additions and 16 deletions
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47
src/backend/optimizer/path/allpaths.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.163 2007/04/21 21:01:44 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.164 2007/05/26 18:23:01 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -45,6 +45,7 @@ static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte);
static void set_dummy_rel_pathlist(RelOptInfo *rel);
static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte);
static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
@ -198,23 +199,14 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
{
/*
* If we can prove we don't need to scan the rel via constraint exclusion,
* set up a single dummy path for it. (Rather than inventing a special
* "dummy" path type, we represent this as an AppendPath with no members.)
* We only need to check for regular baserels; if it's an otherrel, CE
* was already checked in set_append_rel_pathlist().
* set up a single dummy path for it. We only need to check for regular
* baserels; if it's an otherrel, CE was already checked in
* set_append_rel_pathlist().
*/
if (rel->reloptkind == RELOPT_BASEREL &&
relation_excluded_by_constraints(rel, rte))
{
/* Set dummy size estimates --- we leave attr_widths[] as zeroes */
rel->rows = 0;
rel->width = 0;
add_path(rel, (Path *) create_append_path(rel, NIL));
/* Select cheapest path (pretty easy in this case...) */
set_cheapest(rel);
set_dummy_rel_pathlist(rel);
return;
}
@ -330,7 +322,12 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
if (relation_excluded_by_constraints(childrel, childRTE))
{
/* this child need not be scanned, so just disregard it */
/*
* This child need not be scanned, so we can omit it from the
* appendrel. Mark it with a dummy cheapest-path though, in
* case best_appendrel_indexscan() looks at it later.
*/
set_dummy_rel_pathlist(childrel);
continue;
}
@ -425,6 +422,26 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
set_cheapest(rel);
}
/*
* set_dummy_rel_pathlist
* Build a dummy path for a relation that's been excluded by constraints
*
* Rather than inventing a special "dummy" path type, we represent this as an
* AppendPath with no members.
*/
static void
set_dummy_rel_pathlist(RelOptInfo *rel)
{
/* Set dummy size estimates --- we leave attr_widths[] as zeroes */
rel->rows = 0;
rel->width = 0;
add_path(rel, (Path *) create_append_path(rel, NIL));
/* Select cheapest path (pretty easy in this case...) */
set_cheapest(rel);
}
/* quick-and-dirty test to see if any joining is needed */
static bool
has_multiple_baserels(PlannerInfo *root)