diff options
Diffstat (limited to 'src/backend/optimizer/path/equivclass.c')
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 1bc6d15a3e8..b289ea6e65b 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -10,7 +10,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.9 2008/01/09 20:42:27 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.10 2008/03/31 16:59:26 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1639,6 +1639,44 @@ add_child_rel_equivalences(PlannerInfo *root, /* + * mutate_eclass_expressions + * Apply an expression tree mutator to all expressions stored in + * equivalence classes. + * + * This is a bit of a hack ... it's currently needed only by planagg.c, + * which needs to do a global search-and-replace of MIN/MAX Aggrefs + * after eclasses are already set up. Without changing the eclasses too, + * subsequent matching of ORDER BY clauses would fail. + * + * Note that we assume the mutation won't affect relation membership or any + * other properties we keep track of (which is a bit bogus, but by the time + * planagg.c runs, it no longer matters). Also we must be called in the + * main planner memory context. + */ +void +mutate_eclass_expressions(PlannerInfo *root, + Node *(*mutator) (), + void *context) +{ + ListCell *lc1; + + foreach(lc1, root->eq_classes) + { + EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1); + ListCell *lc2; + + foreach(lc2, cur_ec->ec_members) + { + EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2); + + cur_em->em_expr = (Expr *) + mutator((Node *) cur_em->em_expr, context); + } + } +} + + +/* * find_eclass_clauses_for_index_join * Create joinclauses usable for a nestloop-with-inner-indexscan * scanning the given inner rel with the specified set of outer rels. |