Re: count(*) ?

From: shakespeare <>
Date: Wed, 16 Jan 2008 09:33:19 +0100
Message-ID: <478dc155$0$85778$>

"Frank van Bortel" <> schreef in bericht news:7767f$478cff47$524b5c40$
> nick wrote:
>> I understand that when you feed the count( ) function an asterisk as
>> an argument it runs
>> slower than if you use a column name as an argument. Can someone tell
>> me why this is so?
>> Thanks
> Test it - it is not so - who do you believe?!?
> --
> Regards,
> Frank van Bortel
> Top-posting in UseNet newsgroups is one way to shut me up

O yes it is! If you have a sparse column (say col_a), indexed in a very large table, count(col_a) will use the index , where count(*) doesn't (and they will return different values as well). I think you confused this with select (*) and select (1) (which perform the same, although you might find a DBA at your current working place who is convinced that count (8) is faster.....). They ARE not the same though, for count(*) from table in a view will not invalidate a view when a column is added to the table, where count(1) will.....

Shakespeare Received on Wed Jan 16 2008 - 02:33:19 CST

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