... loose-daemon_memcached_option=’-vvv’ 

•If columns specified to hold memcached  values are the wrong data type, such as a numeric type instead of a string type, attempts to store key-value pairs fail with no specific error code or message. 

•If the daemon_memcached  plugin causes MySQL server startup issues, you can temporarily disable the daemon_memcached  plugin while troubleshooting by adding this line under the [mysqld]  group in the MySQL configuration file: 

daemon_memcached=OFF 

For example, if you run the INSTALL PLUGIN  statement before running the innodb_memcached_config.sql  configuration script to set up the necessary database and tables, the server might unexpectedly exit and fail to start. The server could also fail to start if you incorrectly configure an entry in the innodb_memcache.containers  table. 

To uninstall the memcached  plugin for a MySQL instance, issue the following statement: 

mysql> UNINSTALL PLUGIN daemon_memcached; 

•If you run more than one instance of MySQL on the same machine with the daemon_memcached  plugin enabled in each instance, use the daemon_memcached_option  configuration parameter to specify a unique memcached  port for each daemon_memcached  plugin. 

•If an SQL statement cannot find the InnoDB  table or finds no data in the table, but memcached API calls retrieve the expected data, you may be missing an entry for the InnoDB  table in the innodb_memcache.containers  table, or you may have not switched to the correct InnoDB  table by issuing a get  or set  request using @@ table_id  notation. This problem could also occur if you change an existing entry in the innodb_memcache.containers  table without restarting the MySQL server afterward. The free-form storage mechanism is flexible enough that your requests to store or retrieve a multi-column value such as col1|col2|col3  may still work, even if the daemon is using the test.demo_test  table which stores values in a single column. 

•When defining your own InnoDB  table for use with the daemon_memcached  plugin, and columns in the table are defined as NOT NULL , ensure that values are supplied for the NOT NULL  columns when inserting a record for the table into the innodb_memcache.containers  table. If the INSERT statement for the innodb_memcache.containers  record contains fewer delimited values than there are mapped columns, unfilled columns are set to NULL . Attempting to insert a NULL  value into a NOT NULL  column causes the INSERT  to fail, which may only become evident after you reinitialize the daemon_memcached  plugin to apply changes to the innodb_memcache.containers  table. 

•If cas_column  and expire_time_column  fields of the innodb_memcached.containers  table are set to NULL , the following error is returned when attempting to load the memcached  plugin: 

InnoDB_Memcached: column 6 in the entry for config table ’containers’ in database ’innodb_memcache’ has an invalid NULL value. 

The memcached  plugin rejects usage of NULL  in the cas_column  and expire_time_column columns. Set the value of these columns to 0  when the columns are unused. 

•As the length of the memcached  key and values increase, you might encounter size and length limits. 

•When the key exceeds 250 bytes, memcached  operations return an error. This is currently a fixed limit within memcached . 

• InnoDB  table limits may be encountered if values exceed 768 bytes in size, 3072 bytes in size, or half of the innodb_page_size  value. These limits primarily apply if you intend to create an index on a 

