Re: swarm of processes in BIND state?
От | hubert depesz lubaczewski |
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Тема | Re: swarm of processes in BIND state? |
Дата | |
Msg-id | 20160531105324.GA21561@depesz.com обсуждение исходный текст |
Ответ на | Re: swarm of processes in BIND state? (Jeff Janes <jeff.janes@gmail.com>) |
Список | pgsql-general |
On Mon, May 30, 2016 at 11:05:17AM -0700, Jeff Janes wrote: > So my theory is that you deleted a huge number of entries off from > either end of the index, that transaction committed, and that commit > became visible to all. Planning a mergejoin needs to dig through all > those tuples to probe the true end-point. On master, the index > entries quickly get marked as LP_DEAD so future probes don't have to > do all that work, but on the replicas those index hint bits are, for > some unknown to me reason, not getting set. So it has to scour the > all the heap pages which might have the smallest/largest tuple, on > every planning cycle, and that list of pages is very large leading to > occasional IO stalls. This I get, but why was the same backend reading data for all 3 largest tables, while I know for sure (well, 99.9% sure) that no query touches all of them? depesz -- The best thing about modern society is how easy it is to avoid contact with it. http://depesz.com/
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