Slow loading on private-message-topic-tracking-state.json

tgxworld · September 10, 2021, 6:09am

@Hooksmith I have a fix in the pipeline

github.com/discourse/discourse

PERF: Improve query performance all inbox private messages.

discourse:main ← tgxworld:perf_private_message_list

opened 06:01AM - 10 Sep 21 UTC

tgxworld

+35 -14

First reported in https://meta.discourse.org/t/-/202482/19 There are two optimi…zation being applied here: 1. Fetch a user's group id in a seperate query instead of including it as a sub-query. When I tried a subquery, the query plan becomes very inefficient. 1. Join against the `topic_allowed_users` and `topic_allowed_groups` table instead of doing an IN against a subquery where we UNION the `topic_id`s from the two tables. From my profiling, this enables PG to do a backwards index scan on the `index_topics_on_timestamps_private` index.

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Slow loading on private-message-topic-tracking-state.json

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