INSERT INTO "comment_like" ("person_id", "comment_id", "post_id", "score") VALUES (, , , ) ON CONFLICT ("comment_id", "person_id") DO UPDATE SET "person_id" = , "comment_id" = , "post_id" = , "score" = RETURNING "comment_like"."id", "comment_like"."person_id", "comment_like"."comment_id", "comment_like"."post_id", "comment_like"."score", "comment_like"."published"
The server is showing relatively high execution time for this INSERT statement, like 0.4 seconds mean time. Is this form of blended INSERT with UPDATE and RETURNING slower than doing a direct insert? (was misreading data, these are milliseconds, not seconds)
Every time a remote federation Upvote on a comment comes in to Lemmy, it executes this statement.
I did some digging into the database and got a list of indexes, and it is probably slow as it has two keys and 3 indexes, 5 total:
public comment_like idx_comment_like_comment null CREATE INDEX idx_comment_like_comment ON public.comment_like USING btree (comment_id) public comment_like idx_comment_like_post null CREATE INDEX idx_comment_like_post ON public.comment_like USING btree (post_id) public comment_like comment_like_pkey null CREATE UNIQUE INDEX comment_like_pkey ON public.comment_like USING btree (id) public comment_like comment_like_comment_id_person_id_key null CREATE UNIQUE INDEX comment_like_comment_id_person_id_key ON public.comment_like USING btree (comment_id, person_id) public comment_like idx_comment_like_person null CREATE INDEX idx_comment_like_person ON public.comment_like USING btree (person_id)I’m currently in the process of setting up a load testing environment for lemmy, targeted at the DB for the first draft. Using powa and prometheus to look at the real impact. I would assume most of these udpates are HOT, but i’m not sure yet.
BTW: You have a DM already ;)