One 400GB table, One query - Need Tuning Ideas (SQL2005)

Question

I have a single large table which I would like to optimize. I\'m using MS-SQL 2005 server. I\'ll try to describe how it is used and if anyone has any suggestions I would appreci

Answer 1

I think a clustered index on K7 is the only thing of any value. The rest of your where clause has such low selectivity that it's a waste of time.

Unless you can take advantage of some specific knowledge of your values (maybe k5 is only true if k4 < 0, or something), you're pretty much looking at a clustered index scan. Might as well make it the field that you're ordering by.

Looking at the low numbers of distinct values in k3 - k6, you'd probably only need to read < 1.5 million rows to get your top 1 million. That's probably the best you're going to do - especially since any other plan would need you to order by k7 anyway to evaluate your TOP clause.