Re: Synchronous replication: Promotion of Standby to Primary

Hi,

On Wed, May 27, 2009 at 3:27 PM, Kolb, Harald (NSN - DE/Munich)
<harald(dot)kolb(at)nsn(dot)com> wrote:
> In our use case it's important to have a short failover time.
> So everything what keeps the time low, would be good to have.

Yes. I think that it's a matter of priority.

> We already made some failover investigations and got some good results,
> in
> some cases it took less than 1 second after creating the (finish)
> trigger file.
> Surely, with some best case conditions like small DB and less
> modifications.
>
> What use casees do you have in mind when mentioning a few_minutes
> timeframe ?

It's the case where long-term recovery generates a lot of dirty blocks
in buffer pool. It would take a long time to write out all dirty blocks.
Of course, since bgwriter works also during recovery in 8.4, things
might have got better.

> Are there plans to improve the final checkpointing ?

IIRC, in last CommitFest, this improvement was proposed by Simon
as a part of his recovery_infrastructure patch, and was postponed
until 8.5. But, I'm not sure if it will be actually proposed again for 8.5.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center