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kmarshba
Starting Member
24 Posts |
 Posted - 2003-10-10 : 15:22:04
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| I know count(1) is faster but am having a hard time locating some real documentation on why.Does anyone have an answer to this? I'm wondering if it is only faster because it is counting a constant. Is it better to count a column in the clustered index? My query plan shows it is counting the clustered index even with count(*).Thanks! |
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nr
SQLTeam MVY
12543 Posts |
Posted - 2003-10-10 : 15:43:00
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| It's not.SQL server is specifically optimised for count(*) and I prefer that notation.count(*) will count rows from the best index available - just like count(1).I believe there other lesser databases where count(1) is more efficient :).==========================================Cursors are useful if you don't know sql.DTS can be used in a similar way.Beer is not cold and it isn't fizzy. |
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kmarshba
Starting Member
24 Posts |
Posted - 2003-10-10 : 16:25:36
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| Thanks nr!Now to find out the source of that misconception.Kevin |
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nr
SQLTeam MVY
12543 Posts |
Posted - 2003-10-10 : 17:27:59
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| I've seen it stated for Oracle (even in books) but pretty sure it's not true.The only thing to avoid is count(colname) unless that's what you need.count(*) is the best cos I say so.==========================================Cursors are useful if you don't know sql.DTS can be used in a similar way.Beer is not cold and it isn't fizzy. |
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count(1) vs. count(*)