daniel added a comment. Note that our primary use case for usage tracking is purging the parser cache. So we need to track usages for every rendered version of a page that gets stored in the parser cache. When a page is changed or not, and what the revision timestamp is, is really not relevant.
So, we can add tracking entries whenever something is cached. How do we purge stale entries? E.g. we are tracking entries for a rendering in fr, and then the page is re-rendered in fr, without a new revision being created (because a template has changed). We can now compare the new usages for fr with the old usages recorded in the database. But for usage entries that aren't in the new rendering, we don't know if they are used by a rendering for a different language, e.g. de (entity_usage does not track the target language). We can only know that based on eu_touched: if it's larger or equal to page_touched (which gets updated when the page gets re-parsed), then the records are still needed. If touched is smaller than touched, the entries are stale, and no current rendering uses them. So, as far as I can see, we can get rid of eu_touched only if we replace it with eu_cache_key. That would effectively mean tracking usage for each target language separately. That means a lot more rows in this table on multi-lingual projects like commons. For other projects, it would not make a difference. I kind of like the idea of having eu_cache_key in the table: it makes explicit the fact that we are tracking parser cache entries. TASK DETAIL https://phabricator.wikimedia.org/T124737 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: daniel Cc: Aklapper, StudiesWorld, JanZerebecki, aude, daniel, Lydia_Pintscher, hoo, Wikidata-bugs, Mbch331 _______________________________________________ Wikidata-bugs mailing list Wikidata-bugs@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata-bugs
