[Pgpool-general] Problems configuring pgpool-II 3.0 to failover gracefully and load balance queries

[Stephen Sugden]

Regarding session pooling, that makes sense, and is not a major issue. I
think I misread the documentation as implying something different.
Especially the stuff about being able to load balance inside a transaction.

As for the other issues, I'm glad to hear that I'm not wrong to be confused.
I think I'll try the 2.x series release that ships with centos this
afternoon and see if it exhibits the same behaviour.

-Stephen

On Mon, Feb 21, 2011 at 2:21 PM, Guillaume Lelarge
<guillaume at lelarge.info>wrote:

> Le 21/02/2011 19:59, Stephen Sugden a écrit :
> > Hello everybody,
> >
> > I am trying to configure pgpool-II to load balance queries and provide
> > failover for 2 (or more) identical backend servers. The application that
> > will access pgpool only does SELECT queries. The back end servers are
> > written to directly by a custom ETL process (e.g. no slony or pg9
> > replication).
> >
> > In my tests I have observed the following behaviour:
> >
> > - Load Balancing appears to load balance incoming connections, not
> queries.
> > If I open a single connection and execute a series of select queries,
> they
> > all get routed to the same backend. If I open up multiple connections,
> both
> > backends are used.
>
> Which is what we call session pooling. I don't see an issue here.
>
> > - When a node shuts down the pool drops *all* connections. (but
> subsequent
> > connections are correctly only sent to the backend that is still up)
> > - re-adding a node to the pool using pcp_attach_node causes the pool to
> > reset and all current connections will be closed
> >
> > Is this expected behaviour?
>
> Not for the two last ones. Probably Tatsuo could explain that.
>
>
> --
> Guillaume
>  http://www.postgresql.fr
>  http://dalibo.com
>



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