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Repair bug in 8.2's new logic for planning outer joins: we have to allow joins

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that overlap an outer join's min_righthand but aren't fully contained in it,
to support joining within the RHS after having performed an outer join that
can commute with this one.  Aside from the direct fix in make_join_rel(),
fix has_join_restriction() and GEQO's desirable_join() to consider this
possibility.  Per report from Ian Harding.
This commit is contained in:
Tom Lane
2007-02-13 02:31:03 +00:00
parent 849b070707
commit c17117649b
4 changed files with 55 additions and 23 deletions
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39
src/backend/optimizer/path/joinrels.c
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@ -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;
}
}