I'm an absolute idiot. I forgot to run ANALYZE after upgrading PostgreSQL. No wonder it is doing sequential scans all the time and broke my Matrix server completely.
@PeterCxy upgrading everything. monitoring actually looked fine but running ANALYZE is still good practice, just like gentoo users recompiling everything...
@ghost My Mastodon instance also worked fine before ANALYZE because it does not really need that much of index scan to work well. However Matrix is an absolute beast and without index scans it just stalls completely.
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