Optimizer: invalid hint addition renders other hints in the hint set ineffective

[mcdeea]

Bug Report

When there is an invalid hint in a hint set, the behaviour in TiDB is different than MySQL. MySQL respects the other valid hints while TiDB ignore all the hints in the set.

1. Minimal reproduce step (Required)

mysql> SELECT /*+ MAX_EXECUTION_TIME(10) */ SLEEP(5);
mysql> SELECT /*+ MAX_EXECUTION_TIME(10), dtc(name=tt) */ SLEEP(5);

2. What did you expect to see? (Required)

Result from MySQL : Server version: 5.7.44 MySQL Community Server (GPL)

mysql> SELECT /*+ MAX_EXECUTION_TIME(10) */ SLEEP(5);
+----------+
| SLEEP(5) |
+----------+
|        1 |
+----------+
1 row in set (0.01 sec)

mysql> SELECT /*+ MAX_EXECUTION_TIME(10), dtc(name=tt) */ SLEEP(5);
+----------+
| SLEEP(5) |
+----------+
|        1 |
+----------+
1 row in set, 1 warning (0.01 sec) <-  hint MAX_EXECUTION_TIME(5) was respected

3. What did you see instead (Required)

Result from TiDB v6.5.4

mysql> SELECT /*+ MAX_EXECUTION_TIME(5) */ SLEEP(5);
--------------
SELECT /*+ MAX_EXECUTION_TIME(5) */ SLEEP(5)
--------------

+----------+
| SLEEP(5) |
+----------+
|        1 |
+----------+
1 row in set (0.07 sec)

mysql> SELECT /*+ MAX_EXECUTION_TIME(5), dtc(name=tt) */ SLEEP(5);
--------------
SELECT /*+ MAX_EXECUTION_TIME(5), dtc(name=tt) */ SLEEP(5)
--------------

+----------+
| SLEEP(5) |
+----------+
|        0 |
+----------+
1 row in set, 1 warning (5.00 sec)  <-- hint MAX_EXECUTION_TIME(5) was ignored

4. What is your TiDB version? (Required)

6.5.4