Re: Indexes in Oracle 8i?

From: Alexei VORONOV <alexei_voronov_at_yahoo.com>
Date: Wed, 17 Oct 2001 10:47:38 +0200
Message-ID: <9qjgf0$cgf$1@wanadoo.fr>

What you expect as results? Indexes serves to make retrieving data faster. For example, to get all the records which has ACCOUNT_ID=1 you should not go through the whole table to recognise the records satisfying given condition, Oracle takes Index, which is ordered, find the records with ACCOUNT_ID=1 and gives them in the results.
That is why indexes are usually useful for selective fields (when you are searching for a rare (<25%) values), otherwise it's sometimes better not to use indexes.

If you would like to have yours result ordered, you can place ORDER BY close at the and of SELECT statement.

"Raheen Ballard" <rballard34_at_home.com> a écrit dans le message news: mibz7.137500$5A3.44250624_at_news1.rdc2.pa.home.com...
> Hi! I'm using Oracle 8i personal edition and I was trying out some of
the
> Index exercises in my book (Sam's), but my results don't seem to be
correct.
> For instance, I input:
>
>
> create index ID_INDEX on bills( ACCOUNT_ID );
> ========
> and i get back:
>
> NAME AMOUNT ACCOUNT_ID
> ------------------------------ ---------- --------

--


> PHONE COMPANY                        125          1

> POWER COMPANY                        75          1

> RECORD CLUB                               25          2

> SOFTWARE COMPANY                 250          1

> CABLE TV COMPANY                     35          3

> JOE'S CAR PALACE                      350          5

> S.C. STUDENT LOAN                     200          6

> FLORIDA WATER COMPANY          20          1

> U-O-US INSURANCE                      125          5

> DEBTOR'S CREDIT CARD                35          4

>

> Index created.

> =====================

>

>    It tells me that the index was created, but the results are the same as

> if I'd never created the index...am I doing something

> wrong?  I've tried it on several other tables, with same results...

>

> Thx!!!

>

>

>

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Received on Wed Oct 17 2001 - 03:47:38 CDT