Yann Michel <[EMAIL PROTECTED]> writes:

> On Wed, Dec 22, 2004 at 01:52:40PM -0800, Litao Wu wrote:
>> Does the order of columns in the index matter since
>> more than 50% customer_id = 158?
>> I think it does not in Oracle.
>> Will the performance be better if I change index
>> xxx_idx to ("domain", customer_id, created)?
> Well, in Oracle this would of cause matter. Oracle calculates index
> usage by being able to fill all index's attributes from the left to the
> right. If any one attribute within is missing Oracle would not test if
> it is only one attribute missing, or if all other attributes are missing
> within the query's where clause. 

This depends on the version of Oracle you're using. Oracle 9i 
introduced Index Skip Scans:


I don't know whether pg has something similar?

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