Add an automated way to delete unused authority records

[Jane Sandberg]

Having a bunch of unused authority records in Evergreen can really slow down users who are trying to work with authorities. Koha includes a script to run to remove authorities that are not linked to any bib records. It would be nice if Evergreen included something similar: http://git.koha-community.org/gitweb/?p=koha.git;a=blob;f=misc/migration_tools/remove_unused_authorities.pl;h=f4e0ecbf2dc5eff5761ab20a44027ed6876d2db8;hb=refs/heads/master

[Jane Sandberg (sandbergja)]

Thinking about this a bit more, I guess a simple way to do that would be to just issue the following SQL:

`UPDATE authority.record_entry SET deleted=TRUE WHERE NOT deleted AND id NOT IN (SELECT DISTINCT authority FROM authority.bib_linking)`

And then refine that SQL based on specific needs.

[Josh Stompro (u-launchpad-stompro-org)]

Hello Jane, here are my scripts/notes on purging authority records.

https://gist.github.com/stompro/d036829ff1fd4e0fe3dcddf8a75b4e77

This includes really deleting all the authority records at the end, to actually reduce table usage etc.

Josh