https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=42602
--- Comment #1 from Pedro Amorim <[email protected]> --- Created attachment 199149 --> https://bugs.koha-community.org/bugzilla3/attachment.cgi?id=199149&action=edit Bug 42602: REST API search performance improvements belongs_to prefetch is now skipped when related table not referenced in filter or sort A belongs_to embed adds a LEFT JOIN to the main SELECT. MySQL can normally satisfy ORDER BY + LIMIT 20 by walking the sort index and stopping early, but a LEFT JOIN forces a filesort across all matching rows first. On large datasets (e.g. 250k+ patrons) this is significant. When a belongs_to relation is not referenced in the filter or sort parameters, it is now skipped from prefetch. In other words, a LEFT JOIN is only added to the query if a filter or sort on that table exists. Otherwise, the LEFT JOIN is not added. -- You are receiving this mail because: You are watching all bug changes. _______________________________________________ Koha-bugs mailing list [email protected] https://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-bugs website : http://www.koha-community.org/ git : http://git.koha-community.org/ bugs : http://bugs.koha-community.org/
