Message-ID: <004101c46ec2$631ca930$7201a8c0@mst1x5r347kymb>
From: "Iain" <iain@mst.co.jp>
To: "Markus Bertheau" <twanger@bluetwanger.de>,
	<pgsql-sql@postgresql.org>
References: <1090325769.3241.27.camel@dicaprio.akademie1.de>
Subject: Re: surrogate key or not?
Date: Wed, 21 Jul 2004 10:31:03 +0900
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Hi,

for my 2c worth, performance is the least important of the things you need
to consider regarding use of surrogate keys.

I use surrogate keys for all situations except the simplest code/description
tables, and this is only when the code has no meaning to the application. If
there is any possibility that you will want to update or re-use codes
(attaching a different meaning to them) then surrogate keys are the way to
go..

Thus I see it more as an issue of business logic than performance. There are
of course many other considerations with relational theory and stuff like
that which you could debate endlessly. I expect that googling on "surrogate
keys" would yeild interesting results.

Regards
Iain

----- Original Message ----- 
From: "Markus Bertheau" <twanger@bluetwanger.de>
To: <pgsql-sql@postgresql.org>
Sent: Tuesday, July 20, 2004 9:16 PM
Subject: [SQL] surrogate key or not?


> Hi,
>
> I have a database that has types in them with unique names. These types
> are referenced from other tables through a surrogate integer key. I'm
> now wondering if I should eliminate that surrogate key and just use the
> name as the primary key. Afaiu, surrogate keys are primarily there to
> make joining tables or otherwise searching for a record faster, because
> it's faster to compare two integers than it is to compare two strings.
>
> Now when I want to search for a type in types or another table that
> references types(type_id), under what circumstances is it advisable to
> have a surrogate integer key and not use the unique type name? Is
> searching for an integer as fast as is searching for a string when both
> have an index? How many records in the type table do I need to make a
> surrogate key a not unsignificantly faster way to retrieve a row? What
> about joins? Are these the right questions?
>
> Thanks.
>
> -- 
> Markus Bertheau <twanger@bluetwanger.de>
>
>
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