Re: Index organized table
Date: Tue, 17 Jun 2008 02:29:15 GMT
Message-ID: <%jF5k.4303$n9.2554@trndny01>
"buu" <aha_at_a.com> wrote in message
news:1213644908.513887_at_news.vmware.amis.hr...
> anybody??? :(
>
Usually you use an IOT if most of your retrievels are via the primary key.
This is expecially true if you have a multi column primary key and you are
retrieving data via the leading edge of the key. For example, if you had a
payroll application where you have employees and their pay. You might have
the pay table with the primary key of employeeid, datepaid. In most cases
when you do data manipulation with an employee's pay you will do it for all
or a subset of an employee's pay records. For example, an HR application
that shows an employee and their recent pay. Since with the IOT the data in
the table is sorted by the primary key it is more likely that retrieving the
recent pay records for an employee would visit fewer blocks than the same
table as a heap table. (with an index for the primary key - same index and
same values)
Jim Received on Mon Jun 16 2008 - 21:29:15 CDT