Re: [GENERAL] Indexes?

[Vincent Hikida]

I believe that it is better to have a concatenated key of (toDate,FromDate). 
The reason the toDate should come first is that for more "recent" records, 
finding curDates less than toDate is much more selective than finding 
curDates greater than fromDate. Actually I'm not sure if fromDate is that 
helpful either as part of the concatenated key (it probably depends) but 
definitely not by itself.

If your usual query is someEarlyHistoricalDate between toDate and fromDate, 
then the concatenated key should be (fromDate,toDate) instead.

If toDate is sometimes not known, I would use some fixed date far in the 
future rather than a null.

Vincent
----- Original Message ----- 
From: "Bjørn T Johansen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, December 01, 2004 10:11 PM
Subject: [GENERAL] Indexes?


I have a table where I need to use "..where curdate between fromDate and 
toDate".
Is it best to have two indexes, one for FromDate and one for toDate or 
just one index for both the fields?

Regards,
BTJ
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Bjørn T Johansen
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