Merlin Moncure <mmoncure@xxxxxxxxx> writes: > I have a unloaded development server running 8.4b1 that is returning > from a 'select * from pg_locks' in around 5 ms. While the time itself > is not a big deal, I was curious and tested querying locks on a fairly > busy (200-500 tps sustained) running 8.2 on inferior hardware. This > returned (after an initial slower time) in well under 1 ms most of the > time. Is this noteworthy? What factors slow down best case > pg_lock_status() performance? > edit: I bet it's the max_locks_per_transaction parameter. I really > cranked it on the dev box during an experiment, to 16384. > testing...yup that's it. Are there any negative performance > side-effects that could result from (perhaps overly) cranked > max_locks_per_transaction? [squint...] AFAICS the only *direct* cost component in pg_lock_status is the number of locks actually held or awaited. If there's a noticeable component that depends on max_locks_per_transaction, it must be from hash_seq_search() iterating over empty hash buckets. Which is a mighty tight loop. What did you have max_connections set to? regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
