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Couldn't load plugin named 'innodb'

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As part of reviewing storage engines for my work on the upcoming Expert PHP and MySQL book, I finally had an excuse to try out the InnoDB Plugin for MySQL which is now conveniently included with MySQL 5.1 since 5.1.38.

Following the MySQL 5.1 Reference Manual instructions at 13.6. The InnoDB Storage Engine I included the bare minimum as documented to my my.cnf.

[mysqld]
ignore-builtin-innodb
plugin-load=innodb=ha_innodb_plugin.so ;innodb_trx=ha_innodb_plugin.so ;innodb_locks=ha_innodb_plugin.so ;innodb_cmp=ha_innodb_plugin.so ;innodb_cmp_reset=ha_innodb_plugin.so ;innodb_cmpmem=ha_innodb_plugin.so ;innodb_cmpmem_reset=ha_innodb_plugin.so

However to my misfortune the following error occured.

091212 17:45:14 [ERROR] Can't open shared library '/home/rbradfor/mysql/mysql-5.1.41-linux-x86_64-glibc23/lib/plugin/ha_innodb_plugin.so ' (errno: 22 cannot open shared object file: No such file or directory)
091212 17:45:14 [ERROR] Couldn't load plugin named 'innodb' with soname 'ha_innodb_plugin.so '.

I double checked the files were indeed included in the binary release before undertaking a google search, to reveal the official Innodb Plugin Manual page but still not much to go on with the information ” Can’t open shared library library_name — Diagnose the cause from the following message details.”

Back to re-reading the error message, as referenced, I observed there is a trailing space ‘ ‘ ater the plugin name. Observing that I had indeed had this the my.cnf, the result of joining the lines from the MySQL manual which were broken down for presentation means (as noted).

Removed the space, and viola it works.

mysql> show plugins;
+---------------------+----------+--------------------+---------------------+---------+
| Name                | Status   | Type               | Library             | License |
+---------------------+----------+--------------------+---------------------+---------+
| binlog              | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| partition           | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| ARCHIVE             | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| BLACKHOLE           | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| CSV                 | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| FEDERATED           | DISABLED | STORAGE ENGINE     | NULL                | GPL     |
| MEMORY              | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| MyISAM              | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| MRG_MYISAM          | ACTIVE   | STORAGE ENGINE     | NULL                | GPL     |
| InnoDB              | ACTIVE   | STORAGE ENGINE     | ha_innodb_plugin.so | GPL     |
| INNODB_TRX          | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
| INNODB_LOCKS        | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
| INNODB_CMP          | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
| INNODB_CMP_RESET    | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
| INNODB_CMPMEM       | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
| INNODB_CMPMEM_RESET | ACTIVE   | INFORMATION SCHEMA | ha_innodb_plugin.so | GPL     |
+---------------------+----------+--------------------+---------------------+---------+

I would question that this level of pedantic checking is unnecessary. A simple trim on semi-colon ‘;’ separated values could be an easy fix.

A 5.1 QEP nicety – Using join buffer

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I was surprised to find yesterday when using MySQL 5.1.26-rc with a client I’m recommending 5.1 to, some information not seen in the EXPLAIN plan before while reviewing SQL Statements.

Using join buffer

+----+-------------+-------+--------+---------------+--------------+---------+------------------------+-------+----------------------------------------------+
| id | select_type | table | type   | possible_keys | key          | key_len | ref                    | rows  | Extra                                        |
+----+-------------+-------+--------+---------------+--------------+---------+------------------------+-------+----------------------------------------------+
|  1 | SIMPLE      | lr    | ALL    | NULL          | NULL         | NULL    | NULL                   |  1084 | Using where; Using temporary; Using filesort |
|  1 | SIMPLE      | ca    | ref    | update_check  | update_check | 4       | XXXXXXXXXXXXXXXXX      |     4 | Using where; Using index                     |
|  1 | SIMPLE      | ce    | ALL    | NULL          | NULL         | NULL    | NULL                   | 13319 | Using where; Using join buffer               |
|  1 | SIMPLE      | co    | eq_ref | PRIMARY       | PRIMARY      | 4       | XXXXXXXXXXXXXXXXX      |     1 | Using where                                  |
+----+-------------+-------+--------+---------------+--------------+---------+------------------------+-------+----------------------------------------------+
4 rows in set (0.00 sec)
mysql> select version();
+-----------+
| version() |
+-----------+
| 5.1.26-rc |
+-----------+
1 row in set (0.00 sec)

Sergey Petrunia of the MySQL Optimizer team writes about this in Use of join buffer is now visible in EXPLAIN.