Message-ID: <46D83C50.3040409@livedatagroup.com>
Date: Fri, 31 Aug 2007 12:05:36 -0400
From: Pallav Kalva <pkalva@livedatagroup.com>
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: pgsql-performance@postgresql.org
Subject: Re: 8.2 Autovacuum BUG ?
References: <46D83427.60001@livedatagroup.com>
 <25038.1188574775@sss.pgh.pa.us>
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Tom Lane wrote:
> Pallav Kalva <pkalva@livedatagroup.com> writes:
>   
>>     We turned on autovacuums on 8.2 and we have a database which is read 
>> only , it is basically a USPS database used only for address lookups 
>> (only SELECTS, no updates/deletes/inserts).
>>     
>
>   
>>     This database has about 10gig data and yesterday autovacuum started 
>> on this database and all of a sudden I see lot of archive logs generated 
>> during this time, I guess it might have generated close to 3-4gig data 
>> during this period.
>>     
>
> Probably represents freezing of old tuples, which is a WAL-logged
> operation as of 8.2.  Is it likely that the data is 200M transactions
> old?
>   
If nothing changed on these tables how can it freeze old tuples ?
Does it mean that once it reaches 200M transactions it will do the same 
thing all over again ?
If I am doing just SELECTS on these tables ? how can there be any 
transactions ? or SELECTS considered transactions too ?

> 			regards, tom lane
>
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