From: David Rowley Date: Thu, 15 Feb 2024 05:01:28 +0000 (+1300) Subject: Simplify PathKey checking code X-Git-Tag: REL_17_BETA1~880 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0c444a70f2a79d4d7ef6f1af057909839e5b2097;p=thirdparty%2Fpostgresql.git Simplify PathKey checking code pathkeys_useful_for_ordering() contained some needless checks to return 0 when either root->query_pathkeys or pathkeys lists were empty. This is already handled by pathkeys_count_contained_in(), so let's have it do the work instead of having redundant checks. Similarly, in pathkeys_useful_for_grouping(), checking pathkeys is an empty list just before looping over it isn't required. Technically, neither is the list empty check for group_pathkeys, but I felt a bit more work would have to be done to get the equivalent behavior if we'd left it up to the foreach loop to call list_member_ptr(). This was noticed by Andy while he was reviewing a patch to improve the UNION planner. Since that patch adds another function similar to pathkeys_useful_for_ordering() and since I wasn't planning to copy these redundant checks over to the new function, let's adjust the existing code so that both functions will be consistent. Author: Andy Fan Discussion: https://postgr.es/m/87o7cti48f.fsf@163.com --- diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index bcc1b7a9ebe..da6f457a3bf 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -2143,12 +2143,6 @@ pathkeys_useful_for_ordering(PlannerInfo *root, List *pathkeys) { int n_common_pathkeys; - if (root->query_pathkeys == NIL) - return 0; /* no special ordering requested */ - - if (pathkeys == NIL) - return 0; /* unordered path */ - (void) pathkeys_count_contained_in(root->query_pathkeys, pathkeys, &n_common_pathkeys); @@ -2184,10 +2178,6 @@ pathkeys_useful_for_grouping(PlannerInfo *root, List *pathkeys) if (root->group_pathkeys == NIL) return 0; - /* unordered path */ - if (pathkeys == NIL) - return 0; - /* walk the pathkeys and search for matching group key */ foreach(key, pathkeys) {