this post was submitted on 17 Aug 2023
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Lemmy Server Performance

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Lemmy Server Performance

lemmy_server uses the Diesel ORM that automatically generates SQL statements. There are serious performance problems in June and July 2023 preventing Lemmy from scaling. Topics include caching, PostgreSQL extensions for troubleshooting, Client/Server Code/SQL Data/server operator apps/sever operator API (performance and storage monitoring), etc.

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post inclusion, a solid WHERE clause filter before any JOIN on SELECT post (listing of posts) (lemmy.ml)
submitted 1 year ago by [email protected] to c/[email protected]
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[–] [email protected] 3 points 1 year ago

It can't be a simple as a date range, because we want to be inclusive for smaller communities.

  1. paging is a consideration. 1000 posts per community would allow 10 pages of 20 posts.
  2. small communities are defined to be 1000 or less posts, regardless of age
  3. large communities would focus on recency, the 1000 post would be recently created or edited
  4. Edited can be more tricky, either skip for now or focus on how to limit some kind of mass edit from taking over newly published

 

Also a good time to be reminded that the published date isn't reliable for a couple reasons:

  1. problems in the field have been shown with incoming federation data having future published dates on content. kbin in an easy example, but it isn't limited to kbin.
  2. federation can lag due to server overload and problems paths between specific servers, ISP issues, etc. It is rather common to have received a post hours after the published date. Lemmy currently does not track the 'received' date of content.