Re: [Postgres-xc-bugs] WARNING message when getting online backup from Datanode.

[Michael P. <mic...@gm...>]

On Thu, Jul 12, 2012 at 3:31 PM, Tomonari Katsumata <
kat...@po...> wrote:

> Hi, All
>
> I'm testing online backup(PITR) on Postgres-XC 1.0.0.
> And I have a problem.
>
> The manual says bellow.
> http://postgres-xc.sourceforge.net/docs/1_0/continuous-archiving.html
> This section describes PITR for PostgreSQL.
> Because Coordinator and Datanode of Postgres-XC are
> essentially PostgreSQLserver, you can do PITR for
> each Coordinator and Datanode manually.
>
>
> But, it is a difference between vanilla PostgreSQL and Postgres-XC.
> When I do online backup against Datanode, I get some "WARNING" messages.
>
> [example]: Datanode is running with port 15432.
> System Configuration:
> ---------------------
> Architecture : x86_64
>
> Operating Systems : RHEL 5.7 x86_64
>
> Postgres-XC version : Postgres-XC 1.0
>
> Compilers used : gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-51)
> ---------------------
>
> Behabier:
> ---------------------
> $ psql postgres -p 15432 -c "SELECT pg_start_backup('test');"
> WARNING: Do not have a GTM snapshot available
> WARNING: Do not have a GTM snapshot available
> pg_start_backup
> -----------------
> 0/6000020
> (1 row)
>
> $ psql postgres -p 15432 -c "SELECT pg_stop_backup();"
> WARNING: Do not have a GTM snapshot available
> WARNING: Do not have a GTM snapshot available
> NOTICE: pg_stop_backup complete, all required WAL segments have been
> archived
> pg_stop_backup
> ----------------
> 0/60000A0
> (1 row)
> ---------------------
>
>
> Please tell me if it's ignorable WARNING or not.
> And if I can not ignore the WARNING, do I have to
> execute "pg_start/stop_backup"via "EXECUTE DIRECT" command ?
> If so, the manual has to be revised soon.
>
You cannot connect with an application directly to Datanodes as it won't
guarantee global data consistency.
So EXECUTE DIRECT is necessary here, I use it frequently with
pg_start_backup and pg_stop_backup in HA configuration.
I'll try to fix the documentation soon, thanks for pointing that.
-- 
Michael Paquier
http://michael.otacoo.com