sql small discusion

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sql small discusion

asranantha

SSCarpal Tunnel

Points: 4246
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April 23, 2012 at 8:30 am

#267840

1)what is covering index?when we use in sql servr?
2)what dynamic management view and when we use in sql server?

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Sean Lange SSC Guru Points: 286590 More actions · Answer 1

homework or interview?

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Jared SSC Guru Points: 61793 More actions · Answer 2

asranantha (4/23/2012)
1)what is covering index?when we use in sql servr?
2)what dynamic management view and when we use in sql server?

Do you know how to use google? 🙂 There is lots of information out there on both of these and typing the answers here is really not going to give you what you are looking for. Simple answers below:

1. A covering index is an index whose key contains all of the values of a query and subsequently does not require reading anything other than the index.

2. DMVs contain info on lots of stuff in SQL Server and they are used "primarily" for troubleshooting and administration.

Jared
CE - Microsoft

Phil Parkin SSC Guru Points: 246980 More actions · Answer 3

Do you know how to use google?

If you check out the OP's other posts (try this link), you'll rapidly come to the conclusion that the answer is 'no'.

The absence of evidence is not evidence of absence.
Martin Rees

You can lead a horse to water, but a pencil must be lead.
Stan Laurel

Jared SSC Guru Points: 61793 More actions · Answer 4

Phil Parkin (4/23/2012)
Do you know how to use google?
If you check out the OP's other posts (try this link), you'll rapidly come to the conclusion that the answer is 'no'.

ROFL Ok, adding user to my DNR list.

Jared
CE - Microsoft

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 5

SQLKnowItAll (4/23/2012)
1. A covering index is an index whose key contains all of the values of a query and subsequently does not require reading anything other than the index.

Almost, but not quite. The columns don't have to be in the key.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Jared SSC Guru Points: 61793 More actions · Answer 6

GilaMonster (4/23/2012)
SQLKnowItAll (4/23/2012)
1. A covering index is an index whose key contains all of the values of a query and subsequently does not require reading anything other than the index.
Almost, but not quite. The columns don't have to be in the key.

I assume that included columns could be the addition outside of the key? So basically, it is not the key that matters, but that the index itself with key and included columns can satisfy the query. Right? I should pay more attention here and less to the book I am studying for 70-432. Some stuff s not as clear in there... 🙂

Jared
CE - Microsoft