One of my clients recently had a problem where a query with a semi-measly execution cost of .3 was taking 25 seconds to return. Worse, forcing the query to use a suitable index (instead of the PK with accompanying bookmarks) had a cost of 4.8 and returned instantly. Moreover, the query taking 25 seconds was only iterating over a ...

I'm still looking into this one myself. But at this point I'm thinking I may have stumbled on to a bug. Someone explain what's up with the following: -- returns 0123456789 SELECT ISNULL(NULL,'0123456789') -- returns NULL SELECT NULLIF('0123456789','0123456789') -- works, because 01234 is shorter than 0123456789 SELECT ...