diff options
Diffstat (limited to 'src/backend/optimizer/path/joinpath.c')
| -rw-r--r-- | src/backend/optimizer/path/joinpath.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c index 5aedcd15411..39e2ddda906 100644 --- a/src/backend/optimizer/path/joinpath.c +++ b/src/backend/optimizer/path/joinpath.c @@ -126,8 +126,11 @@ add_paths_to_joinrel(PlannerInfo *root, * * We have some special cases: for JOIN_SEMI and JOIN_ANTI, it doesn't * matter since the executor can make the equivalent optimization anyway; - * we need not expend planner cycles on proofs. For JOIN_UNIQUE_INNER, we - * know we're going to force uniqueness of the innerrel below. For + * we need not expend planner cycles on proofs. For JOIN_UNIQUE_INNER, if + * the LHS covers all of the associated semijoin's min_lefthand, then it's + * appropriate to set inner_unique because the path produced by + * create_unique_path will be unique relative to the LHS. (If we have an + * LHS that's only part of the min_lefthand, that is *not* true.) For * JOIN_UNIQUE_OUTER, pass JOIN_INNER to avoid letting that value escape * this module. */ @@ -138,7 +141,8 @@ add_paths_to_joinrel(PlannerInfo *root, extra.inner_unique = false; /* well, unproven */ break; case JOIN_UNIQUE_INNER: - extra.inner_unique = true; + extra.inner_unique = bms_is_subset(sjinfo->min_lefthand, + outerrel->relids); break; case JOIN_UNIQUE_OUTER: extra.inner_unique = innerrel_is_unique(root, outerrel, innerrel, |