May 23, 2012 at 8:57 am
During this incident I used Idera's SQL Diagnostic Manager and SQL Doctor. SQL DM showed there was a big problem because the wait stats were huge. I could tell that performance was very poor from that. I've found SQL DM to be very helpful in monitoring over 30 SQL Servers. I used SQL Doctor to get a rough idea of what indexes might be needed. Neither of these gave me the perfect answer but having helpful tools makes life easier. But both require you to understand the recommendations they give. For the most part, I didn't implement any suggestions I didn't understand.
May 24, 2012 at 9:40 pm
Do you use 'sub-query'? from my try, DTA doesn't drill down into sub-query. I cheated the DTA while tuning by moving sub-query to main query, DTA gave different result.
May 25, 2012 at 8:33 am
Yes, there was a sub-query. I didn't know DTA wouldn't parse that. Thanks!
May 25, 2012 at 5:40 pm
It Depends. I'm pretty sure that DTA evaluates everything that it can "see". That means that the sub-query has to be one that acts more like an inline view than something separate. If it couldn't process sub-queries, it wouldn't be able to evaluate CTE's or derived tables or cross apply or.... and it does all of that quite nicely.
--Jeff Moden
Change is inevitable... Change for the better is not.
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