Re: [PATCH] Unremovable tuple monitoring

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Yeb Havinga <yebhavinga(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Royce Ausburn <royce(dot)ml(at)inomial(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Kevin Grittner <kevin(dot)grittner(at)wicourts(dot)gov>
Subject: Re: [PATCH] Unremovable tuple monitoring
Date: 2011-11-16 14:58:43
Message-ID: 22537.1321455523@sss.pgh.pa.us
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Yeb Havinga <yebhavinga(at)gmail(dot)com> writes:
> On 2011-11-16 15:34, Tom Lane wrote:
>> The dividing line is enormously unstable though. pgstattuple's idea of
>> RecentGlobalXmin could even be significantly different from that of a
>> concurrently running VACUUM. I can see the point of having VACUUM log
>> what it did, but opinions from the peanut gallery aren't worth much.

> I don't understand your the last remark so I want to get it clear: I
> looked up peanut gallery on the wiki. Is 'opinion from the peanut
> gallery' meant to describe my comments as patch reviewer? I'd appreciate
> brutal honesty on this point.

No no no, sorry if you read that as a personal attack. I was trying to
point out that a process running pgstattuple does not have a value of
RecentGlobalXmin that should be considered authoritative --- it is only
a bystander, not the process that might do actual cleanup work.

regards, tom lane

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