Re: Partial Index Usage Performance Question
Date: Tue, 7 Oct 2008 10:48:23 -0700 (PDT)
On Oct 6, 8:14 am, digory <dig..._at_gmx.net> wrote:
> I have a table T with columns A, B, C and an index I over all three
> columns. Further, I have a query which uses columns A and B, but not
> C, i.e.
> SELECT * FROM T WHERE a = ? AND b = ?
> I gather Oracle is able to use index I even though the last column is
> not used. My question is the following: If I write a query like
> SELECT * FROM T WHERE a = ? AND b = ? AND c = ?
> with a condition for C that, for the data in T, is known to be true
> always, will that query be generally slower or faster than the one
> above, or is there no difference in performance, or does it depend on
> the complexity of the index?
> Thanks for a little insight,
Are you thinking of dynamic SQL? Or trying to come up with simple rules to code in "performance?"
-- @home.com is bogus. http://www.infoworld.com/article/08/10/06/40TC-power-myths_1.htmlReceived on Tue Oct 07 2008 - 12:48:23 CDT