From: Steve Crawford <scrawford@pinpointresearch.com>
To: Huang, Suya <Suya.Huang@au.experian.com>
To: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: DB sessions 100 times of DB connections
Date: Tue, 08 Jul 2014 09:28:47 -0700
Message-ID: <53BC1C3F.1000407@pinpointresearch.com> (raw)
In-Reply-To: <D83E55F5F4D99B4A9B4C4E259E6227CD014B3742@AUX1EXC01.apac.experian.local>
References: <D83E55F5F4D99B4A9B4C4E259E6227CD014B36E3@AUX1EXC01.apac.experian.local>
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On 07/03/2014 06:59 PM, Huang, Suya wrote:
>
> BTW, I'm using the pgbadger report to check for peak connections/sessions.
>
> *From:*pgsql-performance-owner@postgresql.org
> [mailto:pgsql-performance-owner@postgresql.org] *On Behalf Of *Huang, Suya
> *Sent:* Friday, July 04, 2014 11:44 AM
> *To:* pgsql-performance@postgresql.org
> *Subject:* [PERFORM] DB sessions 100 times of DB connections
>
> Hi,
>
> We've experienced a DB issue yesterday and after checked the log found
> that the peak sessions is 3000 while the peak DB connections is only
> around 30. The application is having problem of pulling data but no
> warnings in DB log as it doesn't exceed max_connections.
>
> How could this happen? How does sessions/connections work in Postgres?
>
>
As handy as pgbadger is, I have found that its max-connections values
don't pass the "sniff test" as it generally shows peak values that
exceed the configured number of connections. I haven't dug in to find
out why but could conjecture that the fact that log entries are
generally truncated to the nearest second could cause this sort of thing.
Unexpected connection buildup is often a side-effect of something else
like a large resource-intensive query, a query holding locks that
prevent the other connections' queries from completing or a variety of
other things.
If you are looking to solve/prevent the undescribed "issue", please
provide more detail.
-Steve
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To: pgsql-performance@postgresql.org
Cc: scrawford@pinpointresearch.com, Suya.Huang@au.experian.com
Subject: Re: DB sessions 100 times of DB connections
In-Reply-To: <53BC1C3F.1000407@pinpointresearch.com>
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