diff options
| -rw-r--r-- | src/backend/optimizer/util/predtest.c | 48 |
1 files changed, 41 insertions, 7 deletions
diff --git a/src/backend/optimizer/util/predtest.c b/src/backend/optimizer/util/predtest.c index 678f560978d..95312509f10 100644 --- a/src/backend/optimizer/util/predtest.c +++ b/src/backend/optimizer/util/predtest.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/util/predtest.c,v 1.24 2009/01/09 15:46:10 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/util/predtest.c,v 1.25 2009/05/10 22:45:28 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -124,14 +124,31 @@ static void InvalidateOprProofCacheCallBack(Datum arg, int cacheid, ItemPointer bool predicate_implied_by(List *predicate_list, List *restrictinfo_list) { + Node *p, + *r; + if (predicate_list == NIL) return true; /* no predicate: implication is vacuous */ if (restrictinfo_list == NIL) return false; /* no restriction: implication must fail */ - /* Otherwise, away we go ... */ - return predicate_implied_by_recurse((Node *) restrictinfo_list, - (Node *) predicate_list); + /* + * If either input is a single-element list, replace it with its lone + * member; this avoids one useless level of AND-recursion. We only need + * to worry about this at top level, since eval_const_expressions should + * have gotten rid of any trivial ANDs or ORs below that. + */ + if (list_length(predicate_list) == 1) + p = (Node *) linitial(predicate_list); + else + p = (Node *) predicate_list; + if (list_length(restrictinfo_list) == 1) + r = (Node *) linitial(restrictinfo_list); + else + r = (Node *) restrictinfo_list; + + /* And away we go ... */ + return predicate_implied_by_recurse(r, p); } /* @@ -165,14 +182,31 @@ predicate_implied_by(List *predicate_list, List *restrictinfo_list) bool predicate_refuted_by(List *predicate_list, List *restrictinfo_list) { + Node *p, + *r; + if (predicate_list == NIL) return false; /* no predicate: no refutation is possible */ if (restrictinfo_list == NIL) return false; /* no restriction: refutation must fail */ - /* Otherwise, away we go ... */ - return predicate_refuted_by_recurse((Node *) restrictinfo_list, - (Node *) predicate_list); + /* + * If either input is a single-element list, replace it with its lone + * member; this avoids one useless level of AND-recursion. We only need + * to worry about this at top level, since eval_const_expressions should + * have gotten rid of any trivial ANDs or ORs below that. + */ + if (list_length(predicate_list) == 1) + p = (Node *) linitial(predicate_list); + else + p = (Node *) predicate_list; + if (list_length(restrictinfo_list) == 1) + r = (Node *) linitial(restrictinfo_list); + else + r = (Node *) restrictinfo_list; + + /* And away we go ... */ + return predicate_refuted_by_recurse(r, p); } /*---------- |