diff options
Diffstat (limited to 'src/backend/optimizer/plan/initsplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/initsplan.c | 69 |
1 files changed, 36 insertions, 33 deletions
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c index ff2e13ec977..4c7e281866b 100644 --- a/src/backend/optimizer/plan/initsplan.c +++ b/src/backend/optimizer/plan/initsplan.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.64 2001/10/18 16:11:41 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.65 2001/10/25 05:49:33 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -46,7 +46,7 @@ static void add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo, Relids join_relids); static void add_vars_to_targetlist(Query *root, List *vars); static bool qual_is_redundant(Query *root, RestrictInfo *restrictinfo, - List *restrictlist); + List *restrictlist); static void check_mergejoinable(RestrictInfo *restrictinfo); static void check_hashjoinable(RestrictInfo *restrictinfo); @@ -312,10 +312,10 @@ mark_baserels_for_outer_join(Query *root, Relids rels, Relids outerrels) /* * Presently the executor cannot support FOR UPDATE marking of - * rels appearing on the nullable side of an outer join. - * (It's somewhat unclear what that would mean, anyway: what should - * we mark when a result row is generated from no element of the - * nullable relation?) So, complain if target rel is FOR UPDATE. + * rels appearing on the nullable side of an outer join. (It's + * somewhat unclear what that would mean, anyway: what should we + * mark when a result row is generated from no element of the + * nullable relation?) So, complain if target rel is FOR UPDATE. * It's sufficient to make this check once per rel, so do it only * if rel wasn't already known nullable. */ @@ -411,9 +411,9 @@ distribute_qual_to_rels(Query *root, Node *clause, * outerjoinset list of each baserel will show exactly those outer * joins that are below the qual in the join tree. * - * If the qual came from implied-equality deduction, we can evaluate - * the qual at its natural semantic level. - * + * If the qual came from implied-equality deduction, we can evaluate the + * qual at its natural semantic level. + * */ if (isdeduced) { @@ -488,12 +488,13 @@ distribute_qual_to_rels(Query *root, Node *clause, /* * If the clause was deduced from implied equality, check to see - * whether it is redundant with restriction clauses we already have - * for this rel. Note we cannot apply this check to user-written - * clauses, since we haven't found the canonical pathkey sets yet - * while processing user clauses. (NB: no comparable check is done - * in the join-clause case; redundancy will be detected when the - * join clause is moved into a join rel's restriction list.) + * whether it is redundant with restriction clauses we already + * have for this rel. Note we cannot apply this check to + * user-written clauses, since we haven't found the canonical + * pathkey sets yet while processing user clauses. (NB: no + * comparable check is done in the join-clause case; redundancy + * will be detected when the join clause is moved into a join + * rel's restriction list.) */ if (!isdeduced || !qual_is_redundant(root, restrictinfo, rel->baserestrictinfo)) @@ -537,7 +538,6 @@ distribute_qual_to_rels(Query *root, Node *clause, } else { - /* * 'clause' references no rels, and therefore we have no place to * attach it. Shouldn't get here if callers are working properly. @@ -551,8 +551,8 @@ distribute_qual_to_rels(Query *root, Node *clause, * the two sides represent equivalent PathKeyItems for path keys: any * path that is sorted by one side will also be sorted by the other * (as soon as the two rels are joined, that is). Record the key - * equivalence for future use. (We can skip this for a deduced clause, - * since the keys are already known equivalent in that case.) + * equivalence for future use. (We can skip this for a deduced + * clause, since the keys are already known equivalent in that case.) */ if (can_be_equijoin && restrictinfo->mergejoinoperator != InvalidOid && !isdeduced) @@ -681,7 +681,6 @@ process_implied_equality(Query *root, Node *item1, Node *item2, eq_operator = compatible_oper("=", ltype, rtype, true); if (!HeapTupleIsValid(eq_operator)) { - /* * Would it be safe to just not add the equality to the query if * we have no suitable equality operator for the combination of @@ -735,12 +734,12 @@ qual_is_redundant(Query *root, RestrictInfo *restrictinfo, List *restrictlist) { - List *oldquals; - List *olditem; - Node *newleft; - Node *newright; - List *equalvars; - bool someadded; + List *oldquals; + List *olditem; + Node *newleft; + Node *newright; + List *equalvars; + bool someadded; /* * Set cached pathkeys. NB: it is okay to do this now because this @@ -752,6 +751,7 @@ qual_is_redundant(Query *root, /* If different, say "not redundant" (should never happen) */ if (restrictinfo->left_pathkey != restrictinfo->right_pathkey) return false; + /* * Scan existing quals to find those referencing same pathkeys. * Usually there will be few, if any, so build a list of just the @@ -772,24 +772,26 @@ qual_is_redundant(Query *root, } if (oldquals == NIL) return false; + /* * Now, we want to develop a list of Vars that are known equal to the - * left side of the new qual. We traverse the old-quals list repeatedly - * to transitively expand the Vars list. If at any point we find we - * can reach the right-side Var of the new qual, we are done. We give - * up when we can't expand the equalvars list any more. + * left side of the new qual. We traverse the old-quals list + * repeatedly to transitively expand the Vars list. If at any point + * we find we can reach the right-side Var of the new qual, we are + * done. We give up when we can't expand the equalvars list any more. */ newleft = (Node *) get_leftop(restrictinfo->clause); newright = (Node *) get_rightop(restrictinfo->clause); equalvars = makeList1(newleft); - do { + do + { someadded = false; foreach(olditem, oldquals) { RestrictInfo *oldrinfo = (RestrictInfo *) lfirst(olditem); - Node *oldleft = (Node *) get_leftop(oldrinfo->clause); - Node *oldright = (Node *) get_rightop(oldrinfo->clause); - Node *newguy = NULL; + Node *oldleft = (Node *) get_leftop(oldrinfo->clause); + Node *oldright = (Node *) get_rightop(oldrinfo->clause); + Node *newguy = NULL; if (member(oldleft, equalvars)) newguy = oldright; @@ -801,6 +803,7 @@ qual_is_redundant(Query *root, return true; /* we proved new clause is redundant */ equalvars = lcons(newguy, equalvars); someadded = true; + /* * Remove this qual from list, since we don't need it anymore. * Note this doesn't break the foreach() loop, since lremove |