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From: Amit Kapila <amit.kapila@huawei.com>
To: "'Tom Lane'" <tgl@sss.pgh.pa.us>, "'Heikki Linnakangas'"
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Subject: Re: WAL format changes
Date: Tue, 26 Jun 2012 08:44:50 +0530
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From: pgsql-hackers-owner@postgresql.org
[mailto:pgsql-hackers-owner@postgresql.org] On Behalf Of Tom Lane
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
>>  So I think we should change pg_resetxlog -l option to take a WAL file 
>>  name as argument, and fix pg_upgrade accordingly.

> Seems reasonable I guess.  It's really specifying a starting WAL
> location, but only to file granularity, so treating the argument as a
> file name is sort of a type cheat but seems convenient.

> If we do it that way, we'd better validate that the argument is a legal
> WAL file name, so as to catch any cases where somebody tries to do it
> old-style.

> BTW, does pg_resetxlog's logic for setting the default -l value (from
> scanning pg_xlog to find the largest existing file name) still work?
  

It finds the segment number for largest existing file name from pg_xlog and
then compare it with input provided by the 
user for -l Option, if input is greater it will use the input to set in
control file.
	
With Regards,
Amit Kapila.