From: | Richard Huxton <dev(at)archonet(dot)com> |
---|---|
To: | Jay Kang <arrival123(at)gmail(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Questions on Tags table schema |
Date: | 2007-07-30 10:48:55 |
Message-ID: | 46ADC217.7010607@archonet.com |
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Thread: | |
Lists: | pgsql-performance |
Richard Huxton wrote:
>
>> CREATE TABLE car_tags
>> (
>> CarID integer NOT NULL,
>> TagID integer NOT NULL
>> );
> [snip other table defs]
>
> Don't forget CarID isn't really an integer (I mean, you're not going to
> be doing sums with car id's are you?) it's actually just a unique code.
> Of course, computers are particularly fast at dealing with 32-bit integers.
Just realised I haven't explained what I meant by that.
CarID is a different type from PlaneID and TagID. As it happens, we are
using integers to represent them all, but a CarID = 1 is different from
a PlaneID = 1 and although you can numerically compare the two it is an
error to do so.
--
Richard Huxton
Archonet Ltd
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