[Koha-devel] How can I improve this report?

[Doug Kingston]

Report: Authors not in Authorities

SELECT DISTINCT(author) AS heading FROM biblio WHERE author NOT IN (SELECT
ExtractValue(marcxml,'//datafield[@tag="100"]/subfield[@code="a"]') AS
heading FROM auth_header WHERE authtypecode='PERSO_NAME')ORDER BY heading

I am not a SQL expert, but I believe this is doing an unkeyed troll through
every authority record for every biblio (O(Nbibs * Mauths), which is pretty
bad).  I suspect we can do better by trolling Auths once to create a set
and then compare Bib authors against it.  How can we do this?

-Doug-
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