Editing EPrints and MariaDB 10 (section)

== Data Too Long for Field ==
EPrints often uses <tt>VARCHAR(255)</tt> fields.  This can sometime present a problem especially if the text contains special characters which in affect makes the column even less than 255 characters.  Previously MySQL has just truncated data that has got to long but in MariaDB 10 (as well as [[EPrints_and_MySQL_8 | MySQL 8]]) it now just throws an error message.

The main place in EPrints this is a problem is indexing metadata and the full text of documents.  Since [https://github.com/eprints/eprints3.4/issues/247 EPrints 3.4.5], a restriction on the max length of a word that can be indexed has been added to restrict this to 128 characters, this ensures that even if special characters are used the total space required to store the string does not exceed that available to a <tt>VARCHAR(255)</tt> by some margin.

However, if you are running an earlier version of EPrints, the only solution for now is the same as for the "[[#Not Null without Default Value|Not Null without Default Value]]" issue and setting the SQL mode in <tt>/etc/mysql/mysql.conf.d/mysqld.cnf</tt> as follows and then restarting MySQL:
 sql_mode=ONLY_FULL_GROUP_BY,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
Like this other issue it is <tt>STRICT_TRANS_TABLES</tt> that will throw an error rather than quietly truncate, which although also not ideal is generally less problematic as terms that are too long are unlikely ever to be those searched.

[[Category:Installation]]