782803 - Reduce SQL queries needed by Kuma wiki feeds

Status: RESOLVED WORKSFORME

(developer.mozilla.org Graveyard :: Editing, defect, P3)

Description

[Les Orchard [:lorchard]]

Currently, the feeds for Documents and Revisions in Kuma perform 3 SQL queries for each item in the feed. So, if a feed has a limit of 100 items, this fires off 300 DB queries.

It looks like this can be reduced by using prefetch_related() [1] to build a proper JOIN query, but that requires a Django 1.4 upgrade. This could probably be fixed by just using raw SQL, but that feels painful.

[1] https://docs.djangoproject.com/en/1.4/ref/models/querysets/#prefetch-related

Comment 1

[Les Orchard [:lorchard]]

Oh, and the 3 queries are each to wiki_revision (for current_revision), auth_user (for authorship info), and wiki_documenttag (for categories). These could probably just all be rolled into the same request that fetches Documents.

An exception might be wiki_documenttag, at least not without some fancy raw SQL. We may want to refrain from including tag links in feeds, or hide them behind an option.