From: Lewis Kapell <lkapell@setonhome.org>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-admin@postgresql.org
Subject: Re: TOAST behavior in 8.3 and 8.4
Date: Tue, 13 Apr 2010 15:27:14 -0400
Message-ID: <4BC4C592.7020400@setonhome.org> (raw)
In-Reply-To: <4BC4798502000025000307F4@gw.wicourts.gov>
References: <4BC4BBD4.40706@setonhome.org>
<4BC4798502000025000307F4@gw.wicourts.gov>
Thanks for the clarification.
In tuptoaster.h, just above the declaration of TOAST_TUPLES_PER_PAGE,
there is a comment which begins: "while these can be modified without
initdb..."
Does this mean that if I reduce the value of TOAST_TUPLE_THRESHOLD and
rebuild, I can use an existing database cluster without having to run
initdb again?
On 4/13/2010 3:02 PM, Kevin Grittner wrote:
> Lewis Kapell<lkapell@setonhome.org> wrote:
>
>> I don't understand what that '256 bytes' refers to. That is a far
>> cry from 2kb. I would be grateful if anyone can fill in the
>> evident gap in my knowledge here.
>
> It doesn't try to compress anything unless the tuple (row instance)
> as a whole is above TOAST_TUPLE_THRESHOLD. In trying to reduce the
> tuple size, it won't consider compressing column values below a
> certain size. That is where the 256 versus 32 bytes comes in.
>
> -Kevin
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To: pgsql-admin@postgresql.org
Cc: lkapell@setonhome.org, Kevin.Grittner@wicourts.gov
Subject: Re: TOAST behavior in 8.3 and 8.4
In-Reply-To: <4BC4C592.7020400@setonhome.org>
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