Content-Type: text/plain; charset=UTF-8
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Josh Berkus <josh@agliodbs.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember
	this?
From: Alvaro Herrera <alvherre@commandprompt.com>
To: Bruce Momjian <bruce@momjian.us>
In-reply-to: <201008221651.o7MGplA28857@momjian.us>
References: <201008221651.o7MGplA28857@momjian.us>
Date: Mon, 23 Aug 2010 12:14:52 -0400
Message-Id: <1282579975-sup-2769@alvh.no-ip.org>
User-Agent: Sup/git
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Excerpts from Bruce Momjian's message of dom ago 22 12:51:47 -0400 2010:

> Well, the reason that value is 200 million is for pg_clog cleanup, not
> for xid wraparound protection.  The next sentence does relate to xid
> wraparound, but it seems to fit because the previous sentence ends with
> xid wraparound:
> 
>     Note that the system will launch autovacuum processes to
>     prevent wraparound even when autovacuum is otherwise disabled.
> 
> If we were worried about just xid wraparound I assume the value would be
> 2 billion.
> 
> Do you have a suggestion?  Reorder the items?

I'd add another para before that one saying that this value "also"
affects pg_clog truncation.  I agree that putting pg_clog truncation as
the first item here is not an improvement.  For most people, having
those pg_clog files there or not is going to be a wash, compared to data
size.

-- 
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
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