Re: system views for walsender activity

Le 22/06/2010 06:40, Takahiro Itagaki a écrit :
> [...]
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>> I'm of the opinion that this is a 9.1 problem. It needs more thought
>> than we can put into it now --- one obvious question is what about
>> monitoring on the slave side? Another is who should be able to see the
>> data?
>
> Sure. We should research user's demands for monitoring and management
> of replication. I'll report some voices from users as of this moment:
>
> * Managers often ask DBAs "How long standby servers are behind the master?"
> We should provide such methods for DBAs. We have pg_xlog_location()
> functions, but they should be improved for:
> - The returned values are "xxx/yyy" texts, but more useful information
> is the difference of two values. Subtraction functions are required.
> - For easier management, the master server should provide not only
> sent/flush locations but also received/replayed locations for each
> standby servers. Users don't want to access both master and slaves.
>
> * Some developers want to pause and restart replication from the master
> server. They're going to use replication for application version
> managements. They'll pause all replications, and test their new features
> at the master, and restart replication to spread the changes to slaves.
>

I agree on these two.

Something I found lacking when I added support for Hot Standby /
Streaming Replication in pgAdmin (that was a really small patch, there
was not a lot to do) was that one cannot get the actual value of each
recovery.conf parameter. Try a "SHOW primary_conninfo;" and it will
juste reply that primary_conninfo is an unknown parameter. I already
talked about this to Heikki, but didn't get a chance to actually look at
the code.

--
Guillaume
http://www.postgresql.fr
http://dalibo.com