I was recently running a test with multiple client shell processes running psql commands (inserts) when all the client processes appeared to hang simultaneously. I assumed that I had an application deadlock somewhere, but after a few seconds - less than a minute, but certainly noticeable - all the clients picked up again and went on their way.
In the database log at that time there was a "recycling transaction log" message which seems to correspond to the time when the clients were paused, though I don't have it concretely correlated.
I've seen these messages in the log before, and am aware of the need to increase checkpoint_segments, but I wasn't aware that recycling a transaction log could be that damaging to performance. There may have been some local hiccup in this case, but I'm wondering if recycling is known to be a big hit in general, and if I should strive to tune so that it never happens (if that's possible)?

David Parker    Tazz Networks    (401) 709-5130


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