Subject: Re: Reviewing freeze map code
To: Andres Freund <andres@anarazel.de>, Josh berkus <josh@agliodbs.com>
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CC: "Joshua D. Drake" <jd@commandprompt.com>, Robert Haas
	<robertmhaas@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>,
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From: Jim Nasby <Jim.Nasby@BlueTreble.com>
Message-ID: <a9d2206d-3269-e7f6-4040-8220e85249e4@BlueTreble.com>
Date: Tue, 10 May 2016 23:38:01 -0500
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On 5/6/16 4:20 PM, Andres Freund wrote:
> On 2016-05-06 14:15:47 -0700, Josh berkus wrote:
>> For the serious testing, does anyone have a good technique for creating
>> loads which would stress-test vacuum freezing?  It's hard for me to come
>> up with anything which wouldn't be very time-and-resource intensive
>> (like running at 10,000 TPS for a week).
>
> I've changed the limits for freezing options a while back, so you can
> now set autovacuum_freeze_max as low as 100000 (best set
> vacuum_freeze_table_age accordingly).  You'll have to come up with a
> workload that doesn't overwrite all data continuously (otherwise
> there'll never be old rows), but otherwise it should now be fairly easy
> to test that kind of scenario.

There's also been a tool for forcibly advancing XID floating around for 
quite some time. Using that could have the added benefit of verifying 
anti-wrap still works correctly. (Might be worth testing mxid wrap too...)
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
855-TREBLE2 (855-873-2532)   mobile: 512-569-9461


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