From: Jerry Sievers <gsievers19@comcast.net>
To: Bruce Momjian <bruce@momjian.us>
Cc: Jerry Sievers <gsievers19@comcast.net>,
  Stephen Frost <sfrost@snowman.net>,  pgsql-admin@postgresql.org
Subject: Re: Pg-Upgrade standbys via rsync... and avoid sending UNlogged data?
References: <86d1m5b6bi.fsf@jerry.enova.com>
	<20160725163700.GZ4028@tamriel.snowman.net>
	<20160725164329.GA4028@tamriel.snowman.net>
	<86eg6hr58q.fsf@jerry.enova.com> <20160726161946.GA3511@momjian.us>
Date: Tue, 26 Jul 2016 12:22:39 -0500
In-Reply-To: <20160726161946.GA3511@momjian.us> (Bruce Momjian's message of
	"Tue, 26 Jul 2016 12:19:46 -0400")
Message-ID: <86h9bciaao.fsf@jerry.enova.com>
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Bruce Momjian <bruce@momjian.us> writes:

> On Mon, Jul 25, 2016 at 12:34:45PM -0500, Jerry Sievers wrote:
>
>> Stephen Frost <sfrost@snowman.net> writes:
>> 
>> > * Stephen Frost (sfrost@snowman.net) wrote:
>> >
>> >> > I have among others, a 5TB system  w/about 40G of unlogged data.
>> >> 
>> >> Honestly, sending an extra 40G out of 5TB (we're talking less than 1%
>> >> here...) might be worth it to keep the process simple.
>> >
>> > Of course, I realize right after sending this that you aren't sending
>> > the 5TB. :)
>> 
>> Roger that!  Really, the hard link pg-upgrade option and rsync method
>> for standbys is pure beauty :-)
>> 
>> We have only the post-analyze and this unlogged data  problem to deal
>> with. 
>> 
>> The warehouse is our only system with any substantial amount of unlogged
>> data.
>> 
>> Reducing post-analyze delay was solved by me here with our groovy
>> threaded AnalyzMaTron.  I can get a >5TB system done in about 45 minutes
>> w/20 threads.
>
> The only thing I can suggest is to document this limitation, if people
> think it is worth it.

+1

A couple sentences right near the rsync piece in pg_upgrade docs would
 do it.

Caveat:UNNLogged data will be unnecessarily transfered via rsync and
then immediately discarded from standbys when the standbys are started
unless those tables are truncated on the master before the upgrade.

-- 
Jerry Sievers
e: jerry.sievers@comcast.net
p: 312.241.7800


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