f3406a9 is my first attempt at trying to produce a Keywords MetaField.

It should improve the sensitivity and particularly specificity of matching multiple word terms.

It should be backwards compatible with EPrints allowing the existing keywords field to be changed form longtext to keywords.

Its database query efficiency is not great. It would be possible to make the query more effiicient in later versions of MySQL/MariaDB but I have not looked into the feasibility for different SQL generation dependent on database version in EPrints.

The way the field works allows you to enter terms separates by a comma (by default but customisable with the separator field attribute) into the keywords field for an item. Then similarly with search enter terms separated by commas (or whatever separator was chosen for the field). The listing terms allows for spaces or not between the separator I(e.g. comma) and the next term. However, due to limits with earlier MySQL versions only one space like this is permitted when adding keywords for an item. Multiple spaces are permitted when entering terms in the search form.

I think this sufficiently provides the functionality required of a keywords field from a search perspective. Improvements to allow case-sensitivity to be enabled might be useful.