Обсуждение: Are we really using 23 bytes on most machines?

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Are we really using 23 bytes on most machines?

От
"Daniel Westermann (DWE)"
Дата:
Hi,

https://www.postgresql.org/docs/current/storage-page-layout.html
"(occupying 23 bytes on most machines)"

Is this still true? At least on Linux it is 24 bytes:

postgres=# select pg_column_size( row() );

 pg_column_size  
----------------

             24

(1 row)

Regards
Daniel

Re: Are we really using 23 bytes on most machines?

От
Simon Riggs
Дата:
On Tue, 20 Sept 2022 at 13:24, Daniel Westermann (DWE)
<daniel.westermann@dbi-services.com> wrote:
>
> Hi,
>
> https://www.postgresql.org/docs/current/storage-page-layout.html
> "(occupying 23 bytes on most machines)"
>
> Is this still true? At least on Linux it is 24 bytes:
>
> postgres=# select pg_column_size( row() );
>
>  pg_column_size
> ----------------
>
>              24

Yes, but it is MAXALIGNED, which is documented. So the value you see
is correct and matches the docs.

-- 
Simon Riggs                http://www.EnterpriseDB.com/

Re: Are we really using 23 bytes on most machines?

От
"Daniel Westermann (DWE)"
Дата:
Thank you

Send from my Mobile
From: Simon Riggs <simon.riggs@enterprisedb.com>
Sent: Tuesday, September 20, 2022 3:48:02 PM
To: Daniel Westermann (DWE) <daniel.westermann@dbi-services.com>
Cc: pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
Subject: Re: Are we really using 23 bytes on most machines?
 
On Tue, 20 Sept 2022 at 13:24, Daniel Westermann (DWE)
<daniel.westermann@dbi-services.com> wrote:
>
> Hi,
>
> https://www.postgresql.org/docs/current/storage-page-layout.html
> "(occupying 23 bytes on most machines)"
>
> Is this still true? At least on Linux it is 24 bytes:
>
> postgres=# select pg_column_size( row() );
>
>  pg_column_size
> ----------------
>
>              24

Yes, but it is MAXALIGNED, which is documented. So the value you see
is correct and matches the docs.

--
Simon Riggs                http://www.EnterpriseDB.com/