[pgpool-hackers: 485] Re: [pgpool-general: 2762] Re: OTRS

[Yugo Nagata]

Hi Ishii-san,

I heard from someone an idea to use application_name for tuning load balancing,
though I'm not sure how reasonable or useful.

On Tue, 15 Apr 2014 09:57:02 +0900 (JST)
Tatsuo Ishii <ishii at postgresql.org> wrote:

> [Moved to hackers list]
> 
> Hi pgpool hackers,
> 
> There are some demands of fine tuning for load balancing.
> At this point there are two proposales:
> 
> 1) based on client IP address
> 
> 2) based on database and/or table
> 
> I think the fine tuning for load balancing itself is worth to work on,
> but I would like to know any other way to control the knob before
> proceeding further. Suggestions?
> 
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
> 
> > I think we've same problem. When You will implement the client IP address
> > based setting solution, it will solve our problem. Thx!
> > 
> > In the next steps we would like to migrate some our 2 layer (thick clients
> > - more then 100 users from different IP adressess)  application to the
> > pgpool. If we will same Load Balance  problem, we must set out all of
> > client IP address in the config file one by one. I think is it a little bit
> > difficulty useable.
> > 
> > That reason I would like to suggest maybe the database name setting
> > solution more usable instead of IP address if it possible.
> > 
> > If You can implement only the client IP based solution, of course we will
> > be very happy too.
> > 
> > Thanks a lot,
> > Csaba
> > 
> > 
> > 2014-04-12 1:39 GMT+02:00 Tatsuo Ishii <ishii at postgresql.org>:
> > 
> >> > We examined the native replication mode, but our other databases and
> >> > aplications using OIDs, and random values, and I afraid we will be some
> >> > problems. That reason we're staying in streaming replication mode , and
> >> we
> >> > use OTRS without pool in the production area :(
> >>
> >> For random values (i.e. random() function) we will be able to solve
> >> the problem by using similar technique used in handling now(). However
> >> for OID, I have no idea how to solve it.
> >>
> >> > Do you planning in the future releases  some extra Load Balance
> >> parameters?
> >> > I'm thinking of for example white/black list to turn off/on it on the
> >> > databases, tables, etc.
> >>
> >> I found an interesting TODO related to OTRS:
> >>
> >>
> >> http://www.pgpool.net/mediawiki/index.php/TODO#Ability_to_load_balance_based_on_Client_IP
> >>
> >> The original poster of the TODO item proposed an ablility to control
> >> load balancing based on client IP, rather than database and tables
> >> names. Would this help you if it's implemented?
> >>
> >> Best regards,
> >> --
> >> Tatsuo Ishii
> >> SRA OSS, Inc. Japan
> >> English: http://www.sraoss.co.jp/index_en.php
> >> Japanese: http://www.sraoss.co.jp
> >>
> >> > Thanks for your attention,
> >> > Csaba
> >> >
> >> >
> >> > 2014-04-04 9:13 GMT+02:00 Tatsuo Ishii <ishii at postgresql.org>:
> >> >
> >> >> > We're testing it with your suggested 0 backend weight in the slave. It
> >> >> > working fine without load balancing mode.
> >> >> >
> >> >> > We would like to steer clear of the replication lag problems, that
> >> reason
> >> >> > we're using synchronous replication with remote_write level settings.
> >> >>  But
> >> >> > I see it is not enough.
> >> >>
> >> >> No, it's not. PostgreSQL's synchronous replication does not guarantee
> >> >> that on standby sever the log record has been replayed when master
> >> >> returns a commit message. In short, there's always replication lag.
> >> >>
> >> >> > Can You suggest us an useful solution?
> >> >>
> >> >> As long as you use PostgreSQL's streaming replication, there's no
> >> >> solution for replication delay. Possible solution would be:
> >> >>
> >> >> 1) modify your application so that it's ready for replication lag.
> >> >>
> >> >> 2) use pgpool's native replication mode.
> >> >>
> >> >> > Thx,
> >> >> > Csaba
> >> >> >
> >> >> >
> >> >> > 2014-04-02 1:15 GMT+02:00 Tatsuo Ishii <ishii at postgresql.org>:
> >> >> >
> >> >> >> Humm.. there's no error messages in the pgpool log. Maybe the
> >> >> >> replication lag? To make sure that if that is the cause of the
> >> >> >> problem, you could set the slave's backend weight to 0 and restart
> >> >> >> pgpool-II.
> >> >> >>
> >> >> >> Best regards,
> >> >> >> --
> >> >> >> Tatsuo Ishii
> >> >> >> SRA OSS, Inc. Japan
> >> >> >> English: http://www.sraoss.co.jp/index_en.php
> >> >> >> Japanese: http://www.sraoss.co.jp
> >> >> >>
> >> >>
> >>
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-- 
Yugo Nagata <nagata at sraoss.co.jp>