From: Mario Weilguni <mweilguni@sime.com>
To: pgsql-performance@postgresql.org
Cc: Paul Mackay <mackaypaul@gmail.com>
Subject: Re: Physical column size
Date: Thu, 26 Jan 2006 12:22:03 +0100
Message-ID: <200601261222.03526.mweilguni@sime.com> (raw)
In-Reply-To: <786c2f6d0601260206k2201a548p48af7c7fc085d3b2@mail.gmail.com>
References: <786c2f6d0601260206k2201a548p48af7c7fc085d3b2@mail.gmail.com>
Am Donnerstag, 26. Januar 2006 11:06 schrieb Paul Mackay:
> Hi,
>
> I've created a table like this :
> CREATE TABLE tmp_A (
> c "char",
> i int4
> );
>
> And another one
> CREATE TABLE tmp_B (
> i int4,
> ii int4
> );
>
> I then inerted a bit more than 19 million rows in each table (exactly the
> same number of rows in each).
>
> The end result is that the physical size on disk used by table tmp_A is
> exactly the same as table tmp_B (as revealed by the pg_relation_size
> function) ! Given that a "char" field is supposed to be 1 byte in size and
> a int4 4 bytes, shouldn't the tmp_A use a smaller disk space ? Or is it
> that any value, whatever the type, requires at least 4 bytes to be stored ?
I think this is caused by alignment.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: mweilguni@sime.com, pgsql-performance@postgresql.org, mackaypaul@gmail.com
Subject: Re: Physical column size
In-Reply-To: <200601261222.03526.mweilguni@sime.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox