Re: pros and cons

From: ????? ???????? <v.gorbunov_at_protek.ru>
Date: Thu, 1 Apr 2004 13:51:45 +0400
Message-ID: <024701c417ce$f16f6dd0$29160090@protek>

8.1.7.4

SQL> create table t(n number);

Table created.

SQL> create unique index i on t(n);

Index created.

SQL> alter table t add primary key(n);

Table altered.

SQL> alter table t drop primary key;

Table altered.

SQL> select index_name from user_indexes where index_name ='I';

no rows selected

SQL>

• Original Message ----- From: "Tanel Põder" <tanel.poder.003_at_mail.ee> To: <oracle-l_at_freelists.org> Sent: Thursday, April 01, 2004 12:54 PM Subject: Re: pros and cons

> Hi!
>
> > In the case of a unique index, any time you diable the corresponding
> > constraint, the index will be dropped. (It has to be, else the column
> > would still have the unique property, due to the index.)
>
> By the way, whether the index is dropped or not upon PK/UK constraint
> disabling, is dependent on whether the index is system generated or not
(the
> generated column on dba_indexes). You can have an unique index used used
for
> a constraint, but it doesn't get dropped if the index is created manually
> (with create index before constraint creation or during constraint
creation
> using the "using index (create index... )" clause).
>
> Tanel.
>
>
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Received on Thu Apr 01 2004 - 03:49:35 CST