RE: Primary Constraints and Indexes

From: Kimberly Smith <kimberly.smith_at_gmd.fujitsu.com>
Date: Wed, 10 Jan 2001 08:48:29 -0800
Message-Id: <10737.126285@fatcity.com>

You are correct. The second index is not needed. When you create primary or unique keys Oracle will automatically create a unique index.

-----Original Message-----
From: Wayne McGill [mailto:McGillWL_at_navair.navy.mil] Sent: Wednesday, January 10, 2001 7:46 AM To: Multiple recipients of list ORACLE-L Subject: Primary Constraints and Indexes

As a part-time dba, I am confused about the differences between Primary Keys and Indexes.

For example if I create a table "EMPLOYEES" and in the table creation statement I do something like:

     create table ...
        constraint XXX primary key (EMP_ID) using index ...

then later I create an index:

   create index YYY on EMPLOYEE (EMP_ID) ... I know I have created two indexes (the first one system-named and implicitly created and the second name YYY and created explicitly) but do I really need the second index YYY? It seems to me the YYY index is not really needed? Can someone shed some light on this for me.

THANKS, Wayne
McGillWL_at_navair.navy.mil

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Author: Wayne McGill
  INET: McGillWL_at_navair.navy.mil

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