Re: solution has been found but till no explanation

"Alexander Chupin" <chupin_at_hotmail.ru> wrote in message news:98nptn$efj$1_at_soap.pipex.net...
> > Because without such an index, the merest DML on the parent table will
 lock
> > the entire child table from ALL DML for the duration of the transaction.
>
> Firstly, it seems locking entire table occurs not for
> child but for master table. You can easy look it if
> will monitor dba_lock view.

Wrong.

[Quoted] Any DML to a parent table (whether to the primary key or not) will cause the [Quoted] entire child table to be locked unless there is an index on the child field. [Quoted] And that's not discussable, since the literature is emphatic on the subject.

Yes, updates to the child table will involve a lock on the parent table, too, because the foreign key has to be checked. But that is a shared lock, and is not of the same seriousness as the lock on the child table that results from DML on the parent table.

HJR
>
> Secondly, my main question is WHY Oracle behaviour is
> DIFFERENT when trigger for master table is DISABLED
> or ENABLED? (for more details look my previous posting)
>
> Please, before your next post make easy
> experiment which I exactly described in my
> previous letters. If you till see nothing strange
> you can ignore this message.
>
> Thanx for your attention.
>
> WBR, Alexander Chupin
>
>
>
Received on Wed Mar 14 2001 - 14:17:09 CET