What is the type this string? a:1:{s:2:"en";}

The datatype you're showing us here is a serialized variable in PHP.

To serialize or unserialize it, just use these two methods :

http://php.net/manual/en/function.serialize.php

http://www.php.net/manual/en/function.unserialize.php

To store it in MySQL, depends on the size of the serialized data. VARCHAR, TINYTEXT, TEXT, MEDIUMTEXT or BIGTEXT are available.

You could use TEXT or VARCHAR.

Better yet here are some perfomance numbers. But note I believe he was using some indexing his tests.

http://forums.mysql.com/read.php?24,105964,105964

By the looks of it that is a serialized PHP string.

You can use any normal text field to store its data. Which field type you use depends on how long you expect the data to be.

If it's just a blog post title you could use 'varchar'. With 'varchar' you're limited to 255 characters, if you need to store lots of text then you might be better off using a 'text' field.