Re: Index: order of fields

From: <rtproffitt_at_my-deja.com>
Date: Fri, 25 Feb 2000 17:13:00 GMT
Message-ID: <896d6n$v4d$1@nnrp1.deja.com>

Jenda, Dobry Den

I have heard it explained to me by my DBA friend that you want to have the most "different" data come first, then the most similar data come last...This makes the index more efficient.

Therefore, Country would be a poor choice since C or S, many rows would be similar (by the way, I'm guessing C/S, Cech Republic, Slovakia ???)...Perhaps the year or the AGB offers more randomness and can come first.

If you must access the data by country, then maybe a separate index, bitmap style perhaps would help...

I agrees with ccyr, that EXPLAIN can help track down performance issues...

Hope that helps,
Robert Proffitt
Beckman Coulter
California
RTProffitt AT beckman DOT com

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Before you buy. Received on Fri Feb 25 2000 - 11:13:00 CST