Don't try to fix eliminated nbtree array scan keys.

Preprocessing for nbtree index scans allowed array "input" scan keys
already marked eliminated during array-specific preprocessing to be
"fixed up" during preprocessing proper.  This allowed eliminated scan
keys on DESC index columns to spurious have their strategy commuted,
causing assertion failures.

To fix, teach _bt_fix_scankey_strategy to ignore these scan keys.  This
brings it in line with its only caller, _bt_preprocess_keys.

Oversight in commit 5bf748b8, which enhanced nbtree ScalarArrayOp
execution.

Reported-By: Donghang Lin <donghanglin@gmail.com>
Discussion: https://postgr.es/m/CAA=D8a2sHK6CAzZ=0CeafC-Y-MFXbYxnRSHvZTi=+JHu6kAa8Q@mail.gmail.com

diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 2eff34c4aa6a04189e93a2a696855e3d96cbf799..498b8d20358440354db1fa73068d4d73e8e5cade 100644 (file)
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -3394,6 +3394,13 @@ _bt_fix_scankey_strategy(ScanKey skey, int16 *indoption)
                return true;
        }
 
+       if (skey->sk_strategy == InvalidStrategy)
+       {
+               /* Already-eliminated array scan key; don't need to fix anything */
+               Assert(skey->sk_flags & SK_SEARCHARRAY);
+               return true;
+       }
+
        /* Adjust strategy for DESC, if we didn't already */
        if ((addflags & SK_BT_DESC) && !(skey->sk_flags & SK_BT_DESC))
                skey->sk_strategy = BTCommuteStrategyNumber(skey->sk_strategy);