MySQL Bugs: #39335: table_definition

Bug #39335	table_definition_cache must be >= 256
Submitted:	9 Sep 2008 8:38	Modified:	11 Oct 2008 19:29
Reporter:	Morgan Tocker	Email Updates:
Status:	No Feedback	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	5.1.26-rc	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
It doesn't work if I try and create a table_cache less than 256.  On Windows systems, our descriptor limit is 2048, so surely this could become a problem.

Embedded systems may also prefer lower numbers?

How to repeat:
mysql> show global variables like 'table%';
+-------------------------+--------+
| Variable_name           | Value  |
+-------------------------+--------+
| table_definition_cache  | 256    | 
| table_lock_wait_timeout | 50     | 
| table_open_cache        | 64     | 
| table_type              | MyISAM | 
+-------------------------+--------+
4 rows in set (0.00 sec)

mysql> SET GLOBAL table_definition_cache=128;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+---------------------------------------------------------+
| Level   | Code | Message                                                 |
+---------+------+---------------------------------------------------------+
| Warning | 1292 | Truncated incorrect table_definition_cache value: '128' | 
+---------+------+---------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SET GLOBAL table_definition_cache=256;
Query OK, 0 rows affected (0.00 sec)

mysql> SET GLOBAL table_definition_cache=258;
Query OK, 0 rows affected (0.00 sec)

mysql> SET GLOBAL table_definition_cache=250;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> SET GLOBAL table_definition_cache=257;
Query OK, 0 rows affected (0.00 sec)

mysql> SET GLOBAL table_definition_cache=255;
Query OK, 0 rows affected, 1 warning (0.00 sec)

Suggested fix:
Allow a minimum of 0 (don't cache descriptors).

http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#option_mysqld_table_de...

"The table definition cache takes less space and does not use file descriptors"

No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".

Still present in Server version: 5.1.29-rc-community-log MySQL Community Server (GPL).

Nevermind :)