diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 2aa8837880c..e376c49265c 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -1453,7 +1453,7 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel, /* * Consider an append of partial unordered, unparameterized partial paths. */ - if (partial_subpaths_valid) + if (partial_subpaths_valid && partial_subpaths != NIL) { AppendPath *appendpath; ListCell *lc; @@ -1750,9 +1750,11 @@ accumulate_append_subpath(List *subpaths, Path *path) * 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) @@ -1765,13 +1767,14 @@ 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(rel, NIL, NULL, 0, NIL)); /* - * 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); } |