Date: Mon, 28 Jul 2008 17:52:16 -0400
"Brian Selzer" <brian_at_selzer-software.com> wrote in message
> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
> > aarklon_at_gmail.com wrote:
> >> Hi all,
> >> I read the following in a book
> >> 1) we can have several non clustered indexes on a table , but we can
> >> have only one clustered index per table
> >> 2) index on the primary key can be clustered or non clustered
> >> now my question is
> >> 1) to what extent these statements are true ?
> > To the extent the statements accurately describe the physical
> > implementation of a particular dbms, they are true.
> > Theoretically, one can have multiple clustered indexes at the cost of
> > duplicating the data, which of course incurs a cost. Vendors typically
> > assUme nobody would ever want to incur that cost.
> This is bunk. Badour is an idiot. Where there is a clustered index, that
> index /is/ the table--that is, the table is physically stored using
> data structure is in use for indexes--probably b-trees. A table that does
> not have a clustered index, on the other hand, is physically stored as a
> heap. The leaf nodes of a clustered index /are/ the rows of the table.
> leaf nodes of a non-clustered index are either pointers to rows on the
> (where there is no clustered index) or clustered index keys (along with a
> uniquifier [I didn't coin the term, so don't blame me] if the clustered
> index isn't also a unique index). Although it is possible to have
> indexes that cover the entire heading, that is not the same thing as
> multiple clustered indexes.
Though I agree with you, you are not a very nice person. Why the invective re: Badour? Received on Mon Jul 28 2008 - 23:52:16 CEST