I don't think any of that (machine, IO) should matter, seeing that the queries I ran were run under the same circumstances (just a few seconds later/earlier).

As far as I have learnt, group functions like count etc are some of the fastest operations on an RDBMS, and the '*' is intrinsic to the syntax and does not mean anything special, unless you want to try count(distinct column_name).

I have not come across any evidence to support the theories that count(1) uses index and count(*) does not. (I am unable to use explain plan to check it right now).

- radha

-----Original Message-----
From: Luís Manuel Martins Ganhão
[mailto:mssqldba-ezmlmshield-x59367252.[Email address protected]
Sent: Thursday, June 03, 2004 5:43 AM
To: LazyDBA.com Discussion
Subject: RE: Just out of curiosity



The time depends of how the machine, io, etc. are.

You should measure physical and logical io.


Regards,

LG



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