Re: Postmaster not reporting number of connections correctly

"A. Mous" <a.mous@shaw.ca> writes:
> I've been using 8.0 ever since beta 1, and am currently on 8.0.1.  I have
> noticed (in each version) that the number of records in the pg_stat_activity
> table is not always representative of the number of connections to the
> server.  That is, we have an installation at a client's site that runs a
> nightly batch and reports the results of the run back to us.  One of the
> items reported is a count of the number of records in pg_stat_activity (a
> section of the batch is dependent on whether or not any client connections
> exist).  Every now and then we'll see that the number of records in this
> table is zero, when there should always be at least one since our batch is
> connected when it runs.  I've also seen this myself when querying the table
> (zero reported connections).

Is this being checked within a short time after connection?  The stats
views lag behind reality (by up to 500ms, if memory serves).

> Is there a better way of obtaining the number of connections to the
> postmaster?

I think it's a bad idea to imagine that you could ever know that with
certainty --- even if the number is correct when obtained, it could well
be obsolete by the time it's delivered to the client.

            regards, tom lane