Re: Size of tuples

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От Ron Johnson
Тема Re: Size of tuples
Дата
Msg-id 452C0CAC.8080101@cox.net
обсуждение исходный текст
Ответ на Re: Size of tuples  ("Alex Turner" <armtuk@gmail.com>)
Список pgsql-general
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You know, I'd have sworn that I changed "extra 4" to "extra 9"

Sorry.

On 10/10/06 12:49, Alex Turner wrote:
> Awesome - thank you!
>
> Alex
>
> On 10/9/06, *Ron Johnson* <ron.l.johnson@cox.net
> <mailto:ron.l.johnson@cox.net>> wrote:
>
> On 10/09/06 19:10, Alex Turner wrote:
>> I have a table whose definition is basically
>
>> create table foo (
>> a int,
>> b int,
>> c int,
>> d date
>> );
>
>> and when fully populated, select relpages*8192::long/reltuples from
>> pg_class
>> where relname='foo';
>> gives around 52.  Why is it so wide when there are only 4*4=16
> bytes of
>> actual data?
>
> http://www.postgresql.org/docs/faqs.FAQ.html#item4.5
>
>    23  row header (no OIDs)
> + 16  your row size
> +  4  page pointer
>    --
>    43
>
> I'd guess that the extra 4 bytes is from the null bits, page
> overhead, etc.


- --
Ron Johnson, Jr.
Jefferson LA  USA

Is "common sense" really valid?
For example, it is "common sense" to white-power racists that
whites are superior to blacks, and that those with brown skins
are mud people.
However, that "common sense" is obviously wrong.
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