Basic question.... on Index....

Why the name clustered is used in the clustered index? What is exactly
clustered here?
Thanks,
Jessy
Hi,
Physical ordering of data inside the data page will be same as the Index key
order.
The pages in the data chain and the records on the pages are ordered on the
value of the clustered index key. All inserts are made at the point the key
value in the inserted row fits in the ordering sequence.
See more details of cluetsred index in books online.
Thanks
Hari
SQL Server MVP
"Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
news:%23Sy2IfsZFHA.3852@.TK2MSFTNGP10.phx.gbl...
> Why the name clustered is used in the clustered index? What is exactly
> clustered here?
> Thanks,
> Jessy
>
|||Clustered means the index keys and the table are clustered in the same page?
Jessy
"Hari Prasad" <hari_prasad_k@.hotmail.com> wrote in message
news:%23xMrpksZFHA.2128@.TK2MSFTNGP14.phx.gbl...
> Hi,
> Physical ordering of data inside the data page will be same as the Index
key
> order.
> The pages in the data chain and the records on the pages are ordered on
the
> value of the clustered index key. All inserts are made at the point the
key
> value in the inserted row fits in the ordering sequence.
> See more details of cluetsred index in books online.
>
> Thanks
> Hari
> SQL Server MVP
>
> "Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
> news:%23Sy2IfsZFHA.3852@.TK2MSFTNGP10.phx.gbl...
>
|||Hi,
No. There are seperate Index and Data pages. read the below article.
http://msdn.microsoft.com/library/de...es_05_5h6b.asp
Thanks
Hari
SQL Server MVP
"Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
news:%23rDFQpsZFHA.2124@.TK2MSFTNGP14.phx.gbl...
> Clustered means the index keys and the table are clustered in the same
> page?
> Jessy
>
> "Hari Prasad" <hari_prasad_k@.hotmail.com> wrote in message
> news:%23xMrpksZFHA.2128@.TK2MSFTNGP14.phx.gbl...
> key
> the
> key
>
|||"Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
news:#Sy2IfsZFHA.3852@.TK2MSFTNGP10.phx.gbl...
> Why the name clustered is used in the clustered index? What is exactly
> clustered here?
> Thanks,
> Jessy
>
As an example...
A clustered index is sort of like a dictionary. The keys (dictionary words)
are stored in sorted order. If you need to add a new row called Alligator,
then it would be placed in the correct location in the dictionary.
A non-clustered index is more like the index you find at the back of a book.
The index at the back of the book is stored in sorted order, however, it has
page numbers which tell you to go to page xx to find your word. When you
insert a row here, the data will be appended to the end of the table (unless
you have a clustered index on it), and the index at the back of the book
will be updated appropriately.
One thing to note is that when you have a nonclustered index on a table that
has a clustered index, the "page numbers" don't actually point at the pages,
but rather point at the clustered index key (dictionary word from above).
When you do an insert, the nonclustered index has it's row modified and it
then points to the clustered index key and the row is added in the
dictionary order.
HTH
Rick Sawtell
MCT, MCSD, MCDBA
|||Excellent explanation. This is the sort of explanation I was looking
Thank you very much,
Jessy
"Rick Sawtell" <r_sawtell@.hotmail.com> wrote in message
news:OYPXjysZFHA.1456@.TK2MSFTNGP15.phx.gbl...
> "Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
> news:#Sy2IfsZFHA.3852@.TK2MSFTNGP10.phx.gbl...
> As an example...
> A clustered index is sort of like a dictionary. The keys (dictionary
words)
> are stored in sorted order. If you need to add a new row called
Alligator,
> then it would be placed in the correct location in the dictionary.
> A non-clustered index is more like the index you find at the back of a
book.
> The index at the back of the book is stored in sorted order, however, it
has
> page numbers which tell you to go to page xx to find your word. When you
> insert a row here, the data will be appended to the end of the table
(unless
> you have a clustered index on it), and the index at the back of the book
> will be updated appropriately.
> One thing to note is that when you have a nonclustered index on a table
that
> has a clustered index, the "page numbers" don't actually point at the
pages,
> but rather point at the clustered index key (dictionary word from above).
> When you do an insert, the nonclustered index has it's row modified and it
> then points to the clustered index key and the row is added in the
> dictionary order.
> HTH
> Rick Sawtell
> MCT, MCSD, MCDBA
>
>
|||One of the main benefits of clustered indexes is that you can get better
response for range queries or queries with duplicate keys, because the data
is stored on the same or side by side pages. An IO of 1 page will return
multiple rows that satisfy such a query, reducing IO time in a big way.
Wayne Snyder, MCDBA, SQL Server MVP
Mariner, Charlotte, NC
www.mariner-usa.com
(Please respond only to the newsgroups.)
I support the Professional Association of SQL Server (PASS) and it's
community of SQL Server professionals.
www.sqlpass.org
"Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
news:%23Sy2IfsZFHA.3852@.TK2MSFTNGP10.phx.gbl...
> Why the name clustered is used in the clustered index? What is exactly
> clustered here?
> Thanks,
> Jessy
>
|||Hari:
I'm not sure what you mean by this statement. Your statement is true for
non-clustered indexes, but for the clustered index, the index key and the
data are on the same pages and ARE the data pages. The clustered index does
not use Index pages; they are the data pages, at the leaf level.
Sincerely,
Anthony Thomas

"Hari Prasad" <hari_prasad_k@.hotmail.com> wrote in message
news:%23Tcu7vsZFHA.3120@.TK2MSFTNGP12.phx.gbl...
Hi,
No. There are seperate Index and Data pages. read the below article.
http://msdn.microsoft.com/library/de...es_05_5h6b.asp
Thanks
Hari
SQL Server MVP
"Jessy Martin" <Jessy_Smith79@.hotmail.com> wrote in message
news:%23rDFQpsZFHA.2124@.TK2MSFTNGP14.phx.gbl...
> Clustered means the index keys and the table are clustered in the same
> page?
> Jessy
>
> "Hari Prasad" <hari_prasad_k@.hotmail.com> wrote in message
> news:%23xMrpksZFHA.2128@.TK2MSFTNGP14.phx.gbl...
> key
> the
> key
>
sql