Re: Why frequently updated tables are an issue - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Why frequently updated tables are an issue
Date
Msg-id 20714.1087092666@sss.pgh.pa.us
Whole thread Raw
In response to Re: Why frequently updated tables are an issue  (Jan Wieck <JanWieck@Yahoo.com>)
Responses Re: Why frequently updated tables are an issue  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
Jan Wieck <JanWieck@Yahoo.com> writes:
> On 6/12/2004 3:45 PM, Tom Lane wrote:
>> I don't think it would help very much to define a bit like that --- I
>> can't believe that very many pages would contain only frozen tuples,
>> unless you were to adopt an aggressive policy of using VACUUM FREEZE
>> a lot.

> I thought this implies an aggressive policy of freezing everything by 
> default. But I guess there is something I am not aware of that makes 
> aggressive freezing a bad thing.

Well, it means extra I/O to freeze tuples that you otherwise probably
never would.  So it's not obvious that aggressive freezing in hopes of
saving cycles later is a win.

>> It might be interesting though to have some kind of "fast vacuum" mode
>> that doesn't worry about freezing tuples, but only reclaiming dead ones.

> Wouldn't that screw the current FSM population mechanisms? Not that my 
> suggestions above wouldn't do that either :-)

Yeah, that's another "wholesale" mechanism that we'd have to look at
refining.
        regards, tom lane


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