Deian Popov wrote:

> It may return up to 250,000+ records. How given index can become "bad"?
>
>

When it have low selectivity... The cost to read the index pages and the
data pages, result in almost all data pages to be read.. so it's better
to use a natural scan.

A query that results 250k+ records won't be fast... you should add
another filter criteria, or you just display 250k+ records to the user ????

see you !

--
Alexandre Benson Smith
Development
THOR Software e Comercial Ltda
Santo Andre - Sao Paulo - Brazil
www.thorsoftware.com.br