Bug #103555 Wrong result for dot matching newline with REGEXP

• Submitted: 3 May 2021 7:16
• Modified: 3 May 2021 7:38
• Reporter: Jens Hatlak
• Status: Verified
• Category: MySQL Server: Optimizer
• Severity: S3 (Non-critical)
• Version: 5.7
• OS: Any
• CPU Architecture: Any

[3 May 2021 7:16] Jens Hatlak

Description:
https://dev.mysql.com/doc/refman/5.7/en/regexp.html
https://dev.mysql.com/doc/refman/8.0/en/regexp.html

The following example returns 1, not 0:

SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';

How to repeat:
See description

[3 May 2021 7:38] MySQL Verification Team

Hello Jens Hatlak,

Thank you for the report and test case.

- 5.7

 bin/mysql -uroot -S /tmp/mysql_ushastry.sock
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.34 MySQL Community Server (GPL)

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';
+---------------------------------------+
| 'new*\n*line' REGEXP 'new\\*.\\*line' |
+---------------------------------------+
|                                     1 |
+---------------------------------------+
1 row in set (0.00 sec)

- 8.0.24

 bin/mysql -uroot -S /tmp/mysql_ushastry.sock
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.24 MySQL Community Server - GPL

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';
+---------------------------------------+
| 'new*\n*line' REGEXP 'new\\*.\\*line' |
+---------------------------------------+
|                                     0 |
+---------------------------------------+
1 row in set (0.01 sec)

regards,
Umesh

[4 May 2021 5:32] MySQL Verification Team

Given the differing results in 5.7 vs. 8.0, re-categorizing this to code bug.

regards,
Umesh