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

[Koichi S. <koi...@gm...>]

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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