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Re: 8.2 Autovacuum BUG ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Mikko Partio <mpartio(at)gmail(dot)com>, Pallav Kalva <pkalva(at)livedatagroup(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: 8.2 Autovacuum BUG ?
Date: 2007-08-31 19:08:45
Message-ID: 247.1188587325@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Mikko Partio escribi:
>> Off-topic question: the documentation says that XID numbers are 32 bit.
>> Could the XID be 64 bit when running on a 64 bit platform? That would
>> effectively prevent wrap-around issues.

> No, because they would take too much space in tuple headers.

It's worth noting that the patch Florian is working on, to suppress
assignment of XIDs for transactions that never write anything, will make
for a large reduction in the rate of XID consumption in many real-world
applications.  That will reduce the need for tuple freezing and probably
lessen the attraction of wider XIDs even more.

If he gets it done soon (before the HOT dust settles) I will be strongly
tempted to try to sneak it into 8.3 ...

			regards, tom lane

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Subject: Re: 8.2 Autovacuum BUG ?
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