sherifffruitfly (2/10/2012)
Friend of mine told me to order my joins so that the greatest expected number of rows are eliminated soonest. Unfortunately, I've never been clear on just how to do that.
Your friend isn't exactly correct. The optimizer will re-arrange join order to get the best plan, it will also change LEFT JOIN's to RIGHT JOIN's if that is what it thinks is the fastest way to return the data. You supply the FORCE ORDER hint, but unless you are a superstar with the optimizer like Paul White, I wouldn't recommend it. Let the optimizer do it's job.
I think what your friend means is that if you have a customerTypes table that has 10 rows, put that first and then JOIN to the customers table which has 100000 rows, especially if your WHERE clause has customerType = 'RETAIL' so you are only really looking for one customer type. As I said though, the optimizer will do that automatically.
Jack Corbett
Consultant - Straight Path Solutions
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