Fix autovacuum's database sorting.

When db_comparator() was updated to use pg_cmp_s32(), the arguments
were listed in the wrong order.  This caused autovacuum to sort the
databases by their scores in ascending order instead of descending
order.  To fix, swap the arguments to pg_cmp_s32().

Oversight in commit 3b42bdb471.

Reported-by: Хамидуллин Рустам <r.khamidullin@postgrespro.ru>
Author: Хамидуллин Рустам <r.khamidullin@postgrespro.ru>
Discussion: https://postgr.es/m/5c5a7984-b149-b505-7ad9-2a7766c65b55%40postgrespro.ru
Backpatch-through: 17

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index e9aaf24c1bec8d7bf2d6a3e6c2ac04bc17687f9c..0c975d0eda6d78408c80d9d417f8f9b2624d6ef2 100644 (file)
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -1119,8 +1119,8 @@ rebuild_database_list(Oid newdb)
 static int
 db_comparator(const void *a, const void *b)
 {
-       return pg_cmp_s32(((const avl_dbase *) a)->adl_score,
-                                         ((const avl_dbase *) b)->adl_score);
+       return pg_cmp_s32(((const avl_dbase *) b)->adl_score,
+                                         ((const avl_dbase *) a)->adl_score);
 }
 
 /*