Lempster (1/7/2011)

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Jason, thanks for the article. Just one point: after forcing the optimizer to use a Nested Loop you state,

By trying to force the optimizer to use a Nested Loops where the query didn't really warrant it, we did not improve the query and it could be argued that we caused more work to be performed.

Yet you've improved the query time (compared to when no query hint was used) by nearly 50%. Of course the logical reads have gone through the roof and that may or may not be a problem depending on the amount of memory and CPU on the box in question, but if it's just query execution time you're interested in, I would argue that you have improved it.

I definitley agree that in the vast majority of cases one should leave the optimizer to pick the 'best' plan (we should really say 'optimal' as it may take way too long to actually find the 'best' plan) and use query hints with extreme caution.

Thanks

Lempster