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

On Fri, Oct 18, 2013 at 9:24 PM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> Robert Haas escribió:
>
>> A broader complaint I have with this patch is that it almost but
>> not-quite solves a problem I've had a few times in the past: namely,
>> searching through the data directory for data blocks which have LSNs
>> in the future.  This has come up a few times for me, and this tool
>> would make it easier, because I'd be able to run it and look through
>> the output to see which relations have high max-LSN values.  However,
>> it wouldn't be quite enough, because it'd only tell me about the block
>> with the highest LSN in each file, whereas what I'd really want to
>> find is every block with an LSN greater than some threshold value.
>> Maybe I'm pushing the envelope too much by trying to fit that into the
>> framework of this patch, but I can't help thinking we're not going to
>> want both pg_computemaxlsn and pg_findlsnsaftersomethreshold that are
>> 95% the same code, so maybe we ought to rename the utility to
>> something slightly more generic than "pg_computemaxlsn".
>
> Perhaps not coincidentally, I had a need to do this recently.  Perhaps
> we should turn the utility into a generic tool to report existing LSNs,
> with options to 1) report only the highest one in a given file, 2)
> report only those that exceed some threshold.  So maybe pg_reportlsn or
> pg_extractlsn.

How about extending it validate database in more meaningful way and
name it as validatedb.

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