On Fri, Jun 18, 2010 at 04:33, Takahiro Itagaki
<itagaki.takahiro@oss.ntt.co.jp> wrote:
> Hi,
>
> We don't have any statistic views for walsenders in SR's master server
> in 9.0, but such views would be useful to monitor and manage standby
> servers from the master server. I have two ideas for the solution -
> adding a new system view or recycling pg_stat_activity:
>
> 1. Add another system view for walsenders, ex. "pg_stat_replication".
> It would show pid, remote host, and sent location for each walsender.
>
> 2. Make pg_stat_activity to show walsenders. We could use current_query
> to display walsender-specific information, like:
> =# SELECT * FROM my_stat_activity ;
> -[ RECORD 1 ]----+---------------------------------
> datid | 16384
> <snip>
> current_query | SELECT * FROM my_stat_activity ;
> -[ RECORD 2 ]----+---------------------------------
> datid | 0
> datname |
> procpid | 4300
> usesysid | 10
> usename | itagaki
> application_name |
> client_addr | ::1
> client_port | 37710
> backend_start | 2010-06-16 16:47:35.646486+09
> xact_start |
> query_start |
> waiting | f
> current_query | walsender: sent=0/701AAA8
>
> The attached patch is a WIP codes for the case 2, but it might be
> better to design management policy via SQL in 9.1 before such detailed
> implementation. Comments welcome.
I like version 1 much better. It'll be a lot easier for a management
tool to get the data in proper columns and not have to parse it out of
an arbitrary string field.
The downside is that version 1 will require an initdb, and not version
2, right? In that light, #2 is probably the only one we can do for 9.0
(unless we stumble upon other initdb-forcing changes), so maybe we
should do that one as a temporary measure (and if so, note it both in
the documentation and code that it's a temporary thing).
Wouldn't we also need something similar for the receiving end?
-- Magnus HaganderMe: http://www.hagander.net/Work: http://www.redpill-linpro.com/
