Re: Synchronous replication: status of standby side

Em Sex, 2009-06-05 às 16:19 +0900, Fujii Masao escreveu:
> BTW. Which kind of status should be detectable when combining replication
> with Hot Standby? There are several statuses. For example, the last commit
> transaction in the primary server has been;
>
> 1) not sent to the standby server yet.
> 2) sent to the standby, but not written there yet.
> 3) sent and written, but not fsynced yet.
> 4) sent, written and fsynced, but not applied yet.
> 5) etc..

We could have some kind of "table of replication status code" and a
"last status code" or a "history of status codes", which is used by
clients (psql, pgadmin, etc) to shows the replication status.

> And, which server should we ask the status, the primary or the standby server?

Is expected that this information resides in both? For example, take a
status code like "2) sent to the standby, but not written there yet.",
if we expect this in primary, in the stand by must have something like
"2) received from primary, but not written here yet." as status code? I
guess that would be a good way to check whether and how replication is
working in both servers.

I agree with you that this feature should be postponed.

Best Regards,

--
Dickson S. Guedes
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