[GitHub] [guacamole-client] necouchman commented on pull request #711: GUACAMOLE-1573: Slow selection of users on scale on Postgres

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necouchman commented on PR #711:
URL: https://github.com/apache/guacamole-client/pull/711#issuecomment-1207208780

   While I generally lean toward using `JOIN` instead of nested queries in SQL, and I'm skeptical of situations like this, I _think_ this actually makes sense - it is pre-sorting and eliminating potentially a bunch of extra data from the `guacamole_user_history` table that then doesn't have to be `JOIN`ed to the data pulled out of the `guacamole_user` table.
   
   The only situation where I think this may end up being sub-optimal is if, for some reason, the data in the `guacamole_user_history` table is more fragmented or unsorted, and the `ORDER BY start_date DESC` and then `LIMIT 1` cost ends up high, but even in those situations it still may be lower cost than having to pull out all of the `guacamole_user_history` records and `JOIN`ing them.


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