Re: [Postgres-xc-developers] proxy setup on standby server

[Bei Xu <be...@ad...>]

Hi Koichi:
     Thanks for the reply. I still have doubts for item 1.  If we setup
proxy on server 4, do we reconfigure server 4's coordinator/datanodes to
point to server 4's proxy at ALL TIME(after replication is setup, I can
change gtm_host to point to server4's proxy before I bring up slaves) or
only AFTER promotion?


On 3/20/13 11:08 PM, "Koichi Suzuki" <koi...@gm...> wrote:

>1. It's better to have gtm proxy at server 4 when you failover to this
>server.   We need gtm proxy now to failover GTM while
>coordinators/datanodes are running.   When you simply make a copy of
>coordinator/datanode with pg_basebackup and promote them, they will
>try to connect to gtm_proxy at server3.   You need to reconfigure them
>to connect to gtm_proxy at server4.
>
>2. Only one risk is the recovery point could be different from
>component to component, I mean, some transaction may be committed at
>some node but aborted at another because there could be some
>difference in available WAL records.   It may possible to improve the
>core to handle this to some extent but please understand there will be
>some corner case, especially if DDL is involved in such a case.  This
>chance could be small and you may be able to correct this manually or
>this can be allowed in some applications.
>
>Regards;
>----------
>Koichi Suzuki
>
>
>2013/3/21 Bei Xu <be...@ad...>:
>> Hi, I want to set up HA for pgxc, please see below for my current setup.
>>
>> server1: 1 GTM
>> server2: 1 GTM_Standby
>> server3 (master):  1 proxy
>>                                   1 coordinator
>>                                   2 datanode
>>
>> Server4: (stream replication slave) :  1 standalone proxy ??
>>                                   1 replicated coordinator (slave of
>> server3's coordinator)
>>                                    2 replicated datanode  (slave of
>> server3's datanodes)
>>
>>
>> server3's coordinator and datanodes are the master of the server4's
>> coordinator/datanodes by stream replication.
>>
>> Question.
>> 1. Should there be a proxy on server 4?   If not, which proxy  should
>>the
>> server4's coordinator and datanodes pointing to? (I have to specify the
>> gtm_host in postgresql.conf)/
>> 2. Do I have to use synchronous replication vs Asynchrous replication?
>>I am
>> currently using Asynchrnous replication because I think if I use
>> synchronous, slave failour will affect master.
>>
>> 
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>