diff options
Diffstat (limited to 'src/backend/optimizer/path/joinrels.c')
| -rw-r--r-- | src/backend/optimizer/path/joinrels.c | 39 |
1 files changed, 30 insertions, 9 deletions
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index 70e16eeb8e8..e138f9b0aa2 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.84 2007/01/20 20:45:39 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.85 2007/02/13 02:31:03 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -350,8 +350,9 @@ has_join_restriction(PlannerInfo *root, RelOptInfo *rel) /* ignore full joins --- other mechanisms preserve their ordering */ if (ojinfo->is_full_join) continue; - /* anything inside the RHS is definitely restricted */ - if (bms_is_subset(rel->relids, ojinfo->min_righthand)) + /* if it overlaps RHS and isn't yet joined to LHS, it's restricted */ + if (bms_overlap(rel->relids, ojinfo->min_righthand) && + !bms_overlap(rel->relids, ojinfo->min_lefthand)) return true; /* if it's a proper subset of the LHS, it's also restricted */ if (bms_is_subset(rel->relids, ojinfo->min_lefthand) && @@ -468,16 +469,36 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) /*---------- * Otherwise, the proposed join overlaps the RHS but isn't * a valid implementation of this OJ. It might still be - * a valid implementation of some other OJ, however. We have - * to allow this to support the associative identity - * (a LJ b on Pab) LJ c ON Pbc = a LJ (b LJ c ON Pbc) on Pab + * 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 + * OJs 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 OJ. We have to allow this to + * support the associative identity + * (a LJ b on Pab) LJ c ON Pbc = a LJ (b LJ c ON Pbc) on Pab * since joining B directly to C violates the lower OJ's RHS. * We assume that make_outerjoininfo() set things up correctly - * so that we'll only match to the upper OJ if the transformation - * is valid. Set flag here to check at bottom of loop. + * so that we'll only match to some OJ if the join is valid. + * Set flag here to check at bottom of loop. *---------- */ - is_valid_inner = false; + if (bms_overlap(rel1->relids, ojinfo->min_righthand) && + bms_overlap(rel2->relids, ojinfo->min_righthand)) + { + /* seems OK */ + Assert(!bms_overlap(joinrelids, ojinfo->min_lefthand)); + } + else + is_valid_inner = false; } } |