Re: Access Path Tuning

Hi.

 It's not so simple.
 What happens when tou specify 2 index columns in where, but use a  function over a second field:

 SELECT * FROM my_tab
   WHERE F0001 = 12 AND SUBSTR ( F0002,1,5 ) = 'ABCDE';  You still going to see INDEX RANGE SCAN in EXPLAIN.

 But you are correct about the solution :   only TKPROF gives you some CORRECT indirect data .

 HTH. Michael.

In article <950975376.18959.1.pluto.d4ee154e_at_news.demon.nl>,   "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote:
> If you specify a clause on a column that column willl be used. If you
don't
> specify a clause that column will not be used. In a 3 column indexed
when
> you don't specify a clause on column c, column c will not be used
during
> index retrieval.
> You can easily verify that by comparing tkprof results (where each
> intermediate step shows the number of rows retrieved) and the final
outcome.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
> Sybrand Bakker
> Robert & Amelia Webb <rob_at_thewebbfamily.com> wrote in message
> news:88m5vv$jnl$1_at_nntp9.atl.mindspring.net...
> > I am doing some access path tuning on Oracle 7.3.4 / Oracle 8.0.
When I
> use
> > EXPLAIN PLAN I can easily tell which tables are being accessed and
if the
> > access is using an index. Is there a way to tell how many keys of
the
> index
> > are being used?
> >
> > For example if I have an index on 2 columns A and B ( in that
order) where
> A
> > has the same value for all rows and B is unique across all rows it
would
> be
> > extremely helpful to determine if the indexes was being accessed on
a
> match
> > of just column A or on both columns A and B.
> >
> > Thanks,
> >
> > Robert
> >
> >
>
>

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Before you buy. Received on Sun Feb 20 2000 - 14:23:57 CST