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-rw-r--r--src/backend/optimizer/path/allpaths.c21
-rw-r--r--src/backend/optimizer/path/joinrels.c33
2 files changed, 42 insertions, 12 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index f8f4e0b68f3..2091f715d32 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -1607,7 +1607,7 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
* Consider an append of unordered, unparameterized partial paths. Make
* it parallel-aware if possible.
*/
- if (partial_subpaths_valid)
+ if (partial_subpaths_valid && partial_subpaths != NIL)
{
AppendPath *appendpath;
ListCell *lc;
@@ -2004,9 +2004,11 @@ accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths)
* 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 (see also IS_DUMMY_PATH/IS_DUMMY_REL macros).
+ * AppendPath with no members (see also IS_DUMMY_APPEND/IS_DUMMY_REL macros).
*
- * This is exported because inheritance_planner() has need for it.
+ * (See also mark_dummy_rel, which does basically the same thing, but is
+ * typically used to change a rel into dummy state after we already made
+ * paths for it.)
*/
void
set_dummy_rel_pathlist(RelOptInfo *rel)
@@ -2019,14 +2021,15 @@ set_dummy_rel_pathlist(RelOptInfo *rel)
rel->pathlist = NIL;
rel->partial_pathlist = NIL;
+ /* Set up the dummy path */
add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL, NULL,
0, false, NIL, -1));
/*
- * We set the cheapest path immediately, to ensure that IS_DUMMY_REL()
- * will recognize the relation as dummy if anyone asks. This is redundant
- * when we're called from set_rel_size(), but not when called from
- * elsewhere, and doing it twice is harmless anyway.
+ * We set the cheapest-path fields immediately, just in case they were
+ * pointing at some discarded path. This is redundant when we're called
+ * from set_rel_size(), but not when called from elsewhere, and doing it
+ * twice is harmless anyway.
*/
set_cheapest(rel);
}
@@ -3552,12 +3555,12 @@ generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel)
/* Add partitionwise join paths for partitioned child-joins. */
generate_partitionwise_join_paths(root, child_rel);
+ set_cheapest(child_rel);
+
/* Dummy children will not be scanned, so ignore those. */
if (IS_DUMMY_REL(child_rel))
continue;
- set_cheapest(child_rel);
-
#ifdef OPTIMIZER_DEBUG
debug_print_rel(root, child_rel);
#endif
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 6ddf8461257..50fc0c500d0 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -33,7 +33,6 @@ static void make_rels_by_clauseless_joins(PlannerInfo *root,
ListCell *other_rels);
static bool has_join_restriction(PlannerInfo *root, RelOptInfo *rel);
static bool has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel);
-static bool is_dummy_rel(RelOptInfo *rel);
static bool restriction_is_constant_false(List *restrictlist,
RelOptInfo *joinrel,
bool only_pushed_down);
@@ -1192,10 +1191,38 @@ have_dangerous_phv(PlannerInfo *root,
/*
* is_dummy_rel --- has relation been proven empty?
*/
-static bool
+bool
is_dummy_rel(RelOptInfo *rel)
{
- return IS_DUMMY_REL(rel);
+ Path *path;
+
+ /*
+ * A rel that is known dummy will have just one path that is a childless
+ * Append. (Even if somehow it has more paths, a childless Append will
+ * have cost zero and hence should be at the front of the pathlist.)
+ */
+ if (rel->pathlist == NIL)
+ return false;
+ path = (Path *) linitial(rel->pathlist);
+
+ /*
+ * Initially, a dummy path will just be a childless Append. But in later
+ * planning stages we might stick a ProjectSetPath and/or ProjectionPath
+ * on top, since Append can't project. Rather than make assumptions about
+ * which combinations can occur, just descend through whatever we find.
+ */
+ for (;;)
+ {
+ if (IsA(path, ProjectionPath))
+ path = ((ProjectionPath *) path)->subpath;
+ else if (IsA(path, ProjectSetPath))
+ path = ((ProjectSetPath *) path)->subpath;
+ else
+ break;
+ }
+ if (IS_DUMMY_APPEND(path))
+ return true;
+ return false;
}
/*