diff options
Diffstat (limited to 'src/backend/optimizer/path/joinrels.c')
| -rw-r--r-- | src/backend/optimizer/path/joinrels.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index b6c9494fed6..02c7c5ea864 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -467,20 +467,26 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, } else { + /* + * Otherwise, the proposed join overlaps the RHS but isn't a valid + * implementation of this SJ. It might still be a legal join, + * however, if it does not overlap the LHS. + */ + if (bms_overlap(joinrelids, sjinfo->min_lefthand)) + return false; + /*---------- - * Otherwise, the proposed join overlaps the RHS but isn't - * a valid implementation of this SJ. It might still be - * a legal join, however. If both inputs overlap the RHS, - * assume that it's OK. Since the inputs presumably got past - * this function's checks previously, they can't overlap the - * LHS and their violations of the RHS boundary must represent - * SJs that have been determined to commute with this one. + * If both inputs overlap the RHS, assume that it's OK. Since the + * inputs presumably got past this function's checks previously, + * their violations of the RHS boundary must represent SJs that + * have been determined to commute with this one. * We have to allow this to work correctly in cases like * (a LEFT JOIN (b JOIN (c LEFT JOIN d))) * when the c/d join has been determined to commute with the join * to a, and hence d is not part of min_righthand for the upper * join. It should be legal to join b to c/d but this will appear * as a violation of the upper join's RHS. + * * Furthermore, if one input overlaps the RHS and the other does * not, we should still allow the join if it is a valid * implementation of some other SJ. We have to allow this to @@ -496,11 +502,13 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, bms_overlap(rel1->relids, sjinfo->min_righthand) && bms_overlap(rel2->relids, sjinfo->min_righthand)) { - /* seems OK */ - Assert(!bms_overlap(joinrelids, sjinfo->min_lefthand)); + /* both overlap; assume OK */ } else + { + /* one overlaps, the other doesn't (or it's a semijoin) */ is_valid_inner = false; + } } } |