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....@163.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/0c444a70f2a79d4d7ef6f1af057909839e5b2097 Modified Files -------------- src/backend/optimizer/path/pathkeys.c | 10 ---------- 1 file changed, 10 deletions(-)