[pgpool-general: 2526] Re: Common practices for pgpool availability and data replication

[Tatsuo Ishii]

I don't think it's possible because of PostgreSQL's limitation:

In streaming replication, no standby server accepts DMLs in the first
place.

>>  *   synchronous replication:
>>     *   If DML query relates to any of the table from that list, then
>> pgpool would use synchronous replication - send DML to all DBs;

So this part is not possible.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> We were considering the option to implement this functionality. Do you
> think such configuration (my previous mail) is feasible on top of the
> current pgool code base? Would be it difficult to implement?
> 
> Cheers,
> Gintas
> 
> 
> On Mon, Feb 3, 2014 at 1:33 PM, Lazaro Ruben Garcia Martinez <
> lgarciam at vnz.uci.cu> wrote:
> 
>> An hybrid replication is not possible in this moment. Pgpool works in one
>> specific mode, master-slave mode or syncronous replication.
>>
>> Regards.
>> ________________________________________
>> De: Gintautas Sulskus [gingaz at gmail.com]
>> Enviado el: domingo, 02 de febrero de 2014 14:05
>> Para: Lazaro Ruben Garcia Martinez
>> CC: Athanasios | ZenGuard; pgpool-general at pgpool.net
>> Asunto: Re: [pgpool-general: 2505] Re: Common practices for pgpool
>> availability and data replication
>>
>> Thank you.
>>
>> Probably pgpool watchdog is the way to go for the first attempt.
>>
>> Regarding the second point. I had thoughts.. Would be possible to add a
>> hybrid replication, that is:
>>
>>  *   pgpool would have a list of tables that must be synchronously
>> replicated;
>>  *   synchronous replication:
>>     *   If DML query relates to any of the table from that list, then
>> pgpool would use synchronous replication - send DML to all DBs;
>>  *   asynchronous replication:
>>     *   if DML query does not relate to any table from the list, then it
>> would be sent to the master database and be replicated via streaming
>> replication
>>
>> Is such approach technically feasible (if I wanted to add it)? Would it be
>> difficult?
>> I just had a thought, what if pgpool replicates DML query to all servers.
>> How master's streaming replication then behaves?
>>
>> Cheers,
>> Gintas
>>
>>
>> On Thu, Jan 30, 2014 at 2:18 PM, Lazaro Ruben Garcia Martinez <
>> lgarciam at vnz.uci.cu<mailto:lgarciam at vnz.uci.cu>> wrote:
>> For number one you should use watchdog functionality.
>>
>> Regards.
>> ________________________________________
>> De: pgpool-general-bounces at pgpool.net<mailto:
>> pgpool-general-bounces at pgpool.net> [pgpool-general-bounces at pgpool.net
>> <mailto:pgpool-general-bounces at pgpool.net>] En nombre de Athanasios |
>> ZenGuard [athanasios at zenguard.org<mailto:athanasios at zenguard.org>]
>> Enviado el: jueves, 30 de enero de 2014 6:48
>> Para: Gintautas Sulskus
>> CC: pgpool-general at pgpool.net<mailto:pgpool-general at pgpool.net>
>> Asunto: [pgpool-general: 2505] Re: Common practices for pgpool
>> availability and data replication
>>
>> Hi,
>> for point 1) you can use keepalived and two pgpool machines
>>
>>
>> On Thu, Jan 30, 2014 at 12:00 PM, Gintautas Sulskus <gingaz at gmail.com
>> <mailto:gingaz at gmail.com><mailto:gingaz at gmail.com<mailto:gingaz at gmail.com>>>
>> wrote:
>> Dear All,
>>
>> I have a few questions regarding practices with pgpool:
>> 1. Typically pgpool is a single point of failure. What is the common
>> practice to solve this?
>> 2. Some of our data (e.g. 10% tables) must be consistent across the
>> cluster for every transaction. The rest may differ. Is it possible to have
>> a fine-grained replication, where some DMLs would be replicated
>> synchronously and the rest would use asynchronous replication?
>>
>> Thanks!
>>
>> Best Regards,
>> Gintautas
>>
>> _______________________________________________
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>> pgpool-general at pgpool.net<mailto:pgpool-general at pgpool.net>>
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>>
>>
>>
>> ________________________________
>> Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE
>> ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
>> http://www.antiterroristas.cu
>> http://justiciaparaloscinco.wordpress.com
>>
>> Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE
>> ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
>> http://www.antiterroristas.cu
>> http://justiciaparaloscinco.wordpress.com
>>
>>
>>
>> --
>> Best Regards,
>> Gintautas Sulskus
>>
>> ________________________________
>> Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE
>> ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
>> http://www.antiterroristas.cu
>> http://justiciaparaloscinco.wordpress.com
>>
>> Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE
>> ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
>> http://www.antiterroristas.cu
>> http://justiciaparaloscinco.wordpress.com
>>
> 
> 
> 
> -- 
> Best Regards,
> Gintautas Sulskus