Query rewrite on VERSION() function

Hi There,

By using the query rewrite plugin in 5.7.25-28-log Percona Server (GPL), Release 28, Revision c335905 version, i saw tha following strange behaviour.

Below are the steps excuted :

  1. Load and enable the plugin :

mysql -S /var/lib/mysql57-25/mysql.sock < /usr/local/Percona-Server-5.7.25/share/install_rewriter.sql

  1. Load two patterns in query_rewrite.rewrite_rules table

insert into rewrite_rules ( pattern,replacement) values (‘SELECT version()’,‘select ‘5.6.81-4-log’’);

insert into rewrite_rules ( pattern,replacement) values (‘SELECT PASSWORD(‘pippo’)’,‘select ‘5.6.81-4-log’’);

  1. Load the rules in memory :

CALL query_rewrite.flush_rewrite_rules();

When i execute the following query and the uppercase is used for version() function, it seems that the pattern in not matched :

mysql> select version();
±--------------+
| 5.6.81-40-log |
±--------------+
| 5.6.81-40-log |
±--------------+
1 row in set, 1 warning (0.00 sec)

mysql> select VERSION();
±--------------+
| VERSION() |
±--------------+
| 5.7.25-28-log |
±--------------+

By doing the same query but using the second pattern :

mysql> select password(‘pippo’);
±-------------+
| 5.6.81-4-log |
±-------------+
| 5.6.81-4-log |
±-------------+
1 row in set, 1 warning (0.00 sec)

mysql> select PASSWORD(‘pippo’);
±-------------+
| 5.6.81-4-log |
±-------------+
| 5.6.81-4-log |
±-------------+
1 row in set, 1 warning (0.00 sec)

The result is as expected. The rule is hit and the query is rewritten.

My question is why only by using version() call funtion , the rule is escaped and works only if the exact matching between the query and the pattern in rewrite_rules table.

Thanks

Stofa.

Hi,

Is someone has an idea about this issue?

Thanks.