Prev: SSMS doesn't see SSAS or Integration Services in server type drop
Next: HELP: A severe error occurred on the current command.
From: Alan T on 23 Mar 2010 02:13
Is the clustered index similar to the BTree structure?


From: Uri Dimant on 23 Mar 2010 02:59
Alan T
CI and NCI have Btree structure




"Alan T" <alan_NO_SPAM_pltse(a)yahoo.com.au> wrote in message
news:%23GC83$kyKHA.5936(a)TK2MSFTNGP04.phx.gbl...
> Is the clustered index similar to the BTree structure?
>


From: Dan Guzman on 23 Mar 2010 07:41
> Is the clustered index similar to the BTree structure?

Yes, the clustered is a b-tree structure similar to other indexes. The
difference is that the clustered index leaf nodes are also the data actual
pages. With non-clustered indexes, the leaf nodes refer to the data row
using either the clustered index key (if the table has a clustered index) or
the RID (table is a heap).

--
Hope this helps.

Dan Guzman
SQL Server MVP
http://weblogs.sqlteam.com/dang/



From: Jay Konigsberg on 23 Mar 2010 08:55
> Is the clustered index similar to the BTree structure?

All indexes you can create in Microsoft SQL Server (and most indexes in all
other databases) are implemented as b-tree's.

We all get lazy with the notation these days, however, an index usually uses
a "b-tree" and a clustered index uses a "b+-tree". The difference being that
the + indicates a linked list at the leaf node that is used to logically
order the data. As Erland already pointed out, Microsoft also placed the
data in the leaf node of the b+-tree to implement the clustered index, which
with the linked list and disk allocation algorithms, physically orders the
data.

If you Google "b-tree vs. b+ tree" you will get several university hits with
class materials that describe it better. In particular
http://db.ucsd.edu/CSE232W99/Indexing/index.htm seems like a very good set
of pages.

Good luck,
Jay

--
Jay Konigsberg
SQL Server DBA in Sacramento, CA
http://www.linkedin.com/in/jaykonigsberg

Live in Sacramento, CA?
Join the Sacramento SQL Server User Group on LinkedIn
http://www.linkedin.com/groups?home=&gid=2825448&trk=anet_ug_hm&goback=%2Emyg



"Alan T" <alan_NO_SPAM_pltse(a)yahoo.com.au> wrote in message
news:%23GC83$kyKHA.5936(a)TK2MSFTNGP04.phx.gbl...

>
>


 | 
Pages: 1
Prev: SSMS doesn't see SSAS or Integration Services in server type drop
Next: HELP: A severe error occurred on the current command.