Re: Review: Patch to compute Max LSN of Data Pages

Amit Kapila <amit.kapila@huawei.com>

From: Amit Kapila <amit.kapila@huawei.com>

To: "'Andres Freund'" <andres@2ndquadrant.com>, "'Hari Babu'" <haribabu.kommi@huawei.com>

Cc: "'Robert Haas'" <robertmhaas@gmail.com>, "'Josh Berkus'" <josh@agliodbs.com>, <pgsql-hackers@postgresql.org>

Date: 2013-07-08T11:40:43Z

Lists: pgsql-hackers

On Monday, July 08, 2013 4:26 PM Andres Freund wrote:
> On 2013-07-08 16:17:54 +0530, Hari Babu wrote:
> > +    This utility can also be used to decide whether backup is
> required or not when the data page
> > +    in old-master precedes the last applied LSN in old-standby
> (i.e., new-master) at the
> > +    moment of the failover.
> > +   </para>
> > +  </refsect1>
> 
> I don't think this is safe in any interesting set of cases. Am I
> missing
> something?

No, you are not missing anything. It can be only used to find max LSN in
database which can avoid further corruption 

> People falsely thinking that it can be used for this is the primary
> reason for me objecting the patch...

With Regards,
Amit Kapila.