January 12, 2012 at 9:55 pm
Sergiy (1/12/2012)
Explanation:
Nothing is stopping an INDEX SEEK from being used and answer "A" is the correct answer.
Actually something does.
It's named "bookmark lookup".
There is no 'bookmark lookup' in this case as Jeff's explanation of point H reveals: the non-clustered index is covering for the query.
'Bookmark lookup' is out-of-date now: they are referred to as an RID Lookup for a heap, or Key Lookup for a clustered index. The lookup operation is a seek on the clustered index key, or direct navigation to a row locator (RID) if the base table is a heap.
January 15, 2012 at 4:19 pm
SQL Kiwi (1/12/2012)
There is no 'bookmark lookup' in this case as Jeff's explanation of point H reveals: the non-clustered index is covering for the query.
Sounds right.
I need to find out what did I do wrong to make it do scan instead of seek in my test case.
🙂
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Code for TallyGenerator
January 24, 2012 at 1:55 am
Great question, thanks.
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March 15, 2012 at 8:02 am
Thanks for the question. Even though I got it wrong, I learned a lot. 🙂
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seth delconte
http://sqlkeys.com
January 25, 2014 at 5:48 am
I thought answer B is including answer A also, that is why i did not check answer A.
and i did a big mistake by not reading "select 2"
learned a lot through the explanation given by all. thanks every one 🙂
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