Re: swarm of processes in BIND state?

From: hubert depesz lubaczewski <depesz(at)depesz(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: PostgreSQL General <pgsql-general(at)postgresql(dot)org>
Subject: Re: swarm of processes in BIND state?
Date: 2016-05-31 10:53:24
Message-ID: 20160531105324.GA21561@depesz.com
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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

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