Re: using constants

From: Marten Lehmann <lehmannmapson_at_cnm.de>
Date: Thu, 29 Nov 2007 23:19:08 +0100
Message-ID: <5r8sakF1368i6U1@mid.individual.net>

Hello,

> To your first question, as others have said, it is not likely to make
> a difference. If the word defines a well known state, and the name
> will never change, it is just fine. A lookup table may be nice, but
> that depends on the way it is used.

would you say the same is true for joins? What would be faster,

this one?

domains

---

name (pk)
...

records

---

id (pk)
name (fk)
...

for a query like

select * from domains d, records r where d.name = r.name and d.name = 'whatever'

or this one:

domains

---

id (pk)
name (unique)
...

records

---

id (pk)
domain_id (fk)
...

for a query like

select * from domains d, records r where d.id = r.domain_id and d.name = 'whatever'

Mathematically it should be faster to compare two 4 byte non-zero integer values than two at least 8 byte strings. But the first solution is more elegant and intuitive.

Regards
Marten Received on Thu Nov 29 2007 - 16:19:08 CST