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-- By default the postgres statistics collector massively underestimates the
-- number of distinct rooms in `event_search`, which can cause postgres to use
-- table scans for queries for multiple rooms.
--
-- To work around this we can manually tell postgres the number of distinct rooms
-- by setting `n_distinct` (a negative value here is the number of distinct values
-- divided by the number of rows, so -0.01 means on average there are 100 rows per
-- distinct value). We don't need a particularly accurate number here, as a) we just
-- want it to always use index scans and b) our estimate is going to be better than the
-- one made by the statistics collector.

ALTER TABLE event_search ALTER COLUMN room_id SET (n_distinct = -0.01);

-- Ideally we'd do an `ANALYZE event_search (room_id)` here so that
-- the above gets picked up immediately, but that can take a bit of time so we
-- rely on the autovacuum eventually getting run and doing that in the
-- background for us.