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

From Bruce Momjian
Subject Re: Why frequently updated tables are an issue
Date
Msg-id 200406190307.i5J370j16293@candle.pha.pa.us
Whole thread Raw
In response to Re: Why frequently updated tables are an issue  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Is there a TODO here?  No one explained why frozen tuples are important.

---------------------------------------------------------------------------

Tom Lane wrote:
> 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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