Description:
The number sign(#) belongs to character class HINT_CHR_CHAR in the hint lexer, and QB_NAME(`select#1`) is valid to name a query block in the server code. Actually mysql-test supports such writings. However, the core interactive client mysql(1) does not.
The problem is due to the command processing loop in add_line() respects single-line comments in all contexts except for that of client-side multi-line comment. However, hint comments are designed to behave like regular client-side multi-line comments.
It might be introduced by wl#8016 Parser for optimizer hints, and was not recognized by:
commit ab45d19c674341c8e44f73a6b1c5b5c39ee98f9b
Author: V S Murthy Sidagam <venkata.sidagam@oracle.com>
Date: Wed Sep 9 23:05:09 2015 +0530
Description:
1. Hint commentaries are designed to behave like regular /* ... */
commentaries:
SELECT /*+ " */ 1; -- a valid SQL query
However, the mysql client program waits for the closing doublequote
character.
2. There is a similar issue with statement delimiters like ';', ''', '`'
Analysis:
This regression is introduced by the changes of wl#8016. When we are parsing the input string we need to consider '+' as hint character. Which is not handled.
Fix: Introduced a hint flag for ss_comment and while parsing if we come across "+" we are making ss_comment as hint(SSC_HINT) and reseting it when we came across '*/'.
How to repeat:
The current defective behaviors are:
mysql> explain select /*+ QB_NAME(`select#1`) */ 1;
-> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/*+ QB_NAME(`select' at line 1
mysql> explain select /*+ QB_NAME(`select-- `) */ 1;
-> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/*+ QB_NAME(`select' at line 1
The expected behaviors are:
mysql> explain select /*+ QB_NAME(`select#1`) */ 1;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
1 row in set, 1 warning (0.01 sec)
mysql> show warnings;
+-------+------+-----------------------------------------------------------+
| Level | Code | Message |
+-------+------+-----------------------------------------------------------+
| Note | 1003 | /* select#1 */ select /*+ QB_NAME(`select#1`) */ 1 AS `1` |
+-------+------+-----------------------------------------------------------+
1 row in set (0.01 sec)
mysql> explain select /*+ QB_NAME(select#1) */ 1;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------+
1 row in set, 2 warnings (0.00 sec)
mysql> show warnings;
+---------+------+-------------------------------------------------------+
| Level | Code | Message |
+---------+------+-------------------------------------------------------+
| Warning | 1064 | Optimizer hint syntax error near '#1) */ 1' at line 1 |
| Note | 1003 | /* select#1 */ select 1 AS `1` |
+---------+------+-------------------------------------------------------+
2 rows in set (0.01 sec)
Suggested fix:
The core client should allow characters that begin a single-line comment to appear in the c-style hint comment, and let the hint parser to verify the syntax.
The fixing line might be "ss_comment == SSC_NONE" instead, if the other server-side comment should be fixed as well.
diff --git a/client/mysql.cc b/client/mysql.cc
index fde2ad60025..ad612899fc7 100644
--- a/client/mysql.cc
+++ b/client/mysql.cc
@@ -2482,6 +2482,7 @@ static bool add_line(String &buffer, char *line, size_t line_length,
}
buffer.length(0);
} else if (!*ml_comment &&
+ ss_comment != SSC_HINT &&
(!*in_string &&
(inchar == '#' ||
(inchar == '-' && pos[1] == '-' &&
