doctrine/dbal — pull request #273 by ludekstepan (2013-02-17 18:24:38+00:00)
Title: Use BLOB for Object mapping type

http://php.net/manual/en/function.serialize.php
> Note that this is a binary string which may include null bytes, and needs to be stored and handled as such. For example, serialize() output should generally be stored in a BLOB field in a database, rather than a CHAR or TEXT field.