Howard J. Rogers wrote:
Page 17: "MSSQL provides the ability to create a so-called computed
column and the ability to create an index on this column. [This is
basically equivalent to Oracle's function based index.]" No it's not.
The whole point of the FBI is not to have the computed values resident
in the table, but to be able to nonetheless treat them as
index-searchable. The MS approach merely adds the data into the table
(after which it can obviously be index-searched).
--
Actually SQL Server 2005 allegedly supports both virtual computed
columns and "persisted" (I think that's their word) computed columns.
The former was introduced in SQL Server 2000.
When used in an index a virtial computed column should have similar
charcteristics to FBI (i.e no space allocated in the datapage).
The difference shows up when you do "SELECT *"...
FWIW I too find the article rather shallow. What stunns me most however
is that a product that is being sold today is compared to one that is,
as far as I am concerned, still vaporware.
Presumably O10gR2 will be more than a bugfix release and will ship in
the same timeframe, if not earlier than SQL Server 2005.
Cheers
Serge
Received on Sun Nov 21 2004 - 07:14:08 CST
