Re: Standalone synchronous master

On Wed, Nov 13, 2013 at 6:39 PM, Rajeev rastogi
<rajeev(dot)rastogi(at)huawei(dot)com> wrote:

> Add a new "eager" synchronous mode that starts out synchronous but reverts
> to asynchronous after a failure timeout period
>
> This would require some type of command to be executed to alert
> administrators of this change.
>
> http://archives.postgresql.org/pgsql-hackers/2011-12/msg01224.php
> This patch implementation is in the same line as it was given in the earlier
> thread.
>
> Some Of the additional important changes are:
>
> 1. Have added two GUC variable to take commands from user to be
> executed
>
> a. Master_to_standalone_cmd: To be executed before master switches to
> standalone mode.
>
> b. Master_to_sync_cmd: To be executed before master switches from sync
> mode to standalone mode.

In description of both switches (a & b), you are telling that it
will switch to
standalone mode, I think by your point 1b. you mean to say other way
(switch from standalone to sync mode).

Instead of getting commands, why can't we just log such actions? I think
adding 3 new guc variables for this functionality seems to be bit high.

Also what will happen when it switches to standalone mode incase there
are some async standby's already connected to it before going to
standalone mode, if it continues to send data then I think naming it as
'enable_standalone_master' is not good.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com