Re: pros and cons
- From: "????? ????????" <v.gorbunov@xxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 1 Apr 2004 13:51:45 +0400
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@xxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
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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