[pgpool-general: 2757] Re: OTRS

[Tatsuo Ishii]

> 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
>> >>
>>