Re: Query optimisation

Geoff Dewhurst wrote:

> It uses the index like it should, however, when I change the statement to :
> SELECT CODE FROM CLR WHERE CLRIDX = 1;
> the index is not used!!! Can anyone explain this?

It uses index when field is highly selective-small variance and can scan less than 20% of rows, otherwise it uses full table scan.

Grinalds Received on Tue Nov 25 1997 - 00:00:00 CST