To monitor the number of PostgreSQL database connections?

On Wed, Mar 26, 2014 at 11:01:28AM +0530, Nithya Soman wrote:

Hi

Could you please provide any method (query or any logfile) to check
max connections happened during a time interval in psql DB ?

I think there will be a message in the logs when you exceed
max_connections. I think the error string will be:

sorry, too many clients already

That is kind of an odd message.

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EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +

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I know this isn't exactly what you're looking for (a query or log), but we
use this tool to monitor our connections and alert when they hit a
particular threshold:

http://bucardo.org/check_postgres/check_postgres.pl.html#backends

On Wed, Mar 26, 2014 at 12:31 AM, Nithya Soman
<nithya@quintetsolutions.com>wrote:

Nithya Soman wrote

Hi

Could you please provide any method (query or any logfile) to check
max connections happened during a time interval in psql DB ?

Only if the time interval desired in basically zero-width (i.e.,
instantaneous). The "pg_stat_activity" view is your friend in this.

You have numerous options, including self-coding, for capturing and
historically reviewing these snapshots and/or setting up monitoring on them.

This presumes you are actually wondering "over any given time period how
many open connections were there"? If your question is actually "In the
given time period did any clients get rejected because {max connections}
were already in use." you can check the PostgreSQL logs for the relevant
error.

Bruce basically said this question while Brian answered the first question.

David J.

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On Wed, Mar 26, 2014 at 7:02 PM, David Johnston <polobo@yahoo.com> wrote:

Nithya Soman wrote

Hi

Could you please provide any method (query or any logfile) to check
max connections happened during a time interval in psql DB ?

Only if the time interval desired in basically zero-width (i.e.,
instantaneous). The "pg_stat_activity" view is your friend in this.

You have numerous options, including self-coding, for capturing and
historically reviewing these snapshots and/or setting up monitoring on them.

This presumes you are actually wondering "over any given time period how
many open connections were there"? If your question is actually "In the
given time period did any clients get rejected because {max connections}
were already in use." you can check the PostgreSQL logs for the relevant
error.

There's also some useful high level statistics (including connection
count) in pg_stat_database. For exact connection count over time
frame, I'd turn on log_connections in postgresql.conf and grep the
log.

merlin

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And also you can monitor by scheduling below command in cron. It will
collect the detailed data, so that we came to know where the connections
are coming.

[postgres@local~]$ crontab -l
* * * * * /opt/postgres/9.3/bin/psql -Aqt -p 5493 -c "select * from
pg_stat_activity;" >>/tmp/stats.csv

On Thu, Mar 27, 2014 at 10:20 PM, Merlin Moncure <mmoncure@gmail.com> wrote: