Re: enqueue waits

The enqueues (locks) are occurring because another session has an incompatible lock mode.

A DELETE needs SX (sub exclusive lock) mode to perform the delete. Any session holding a higher mode lock (S, SSX, X) will block this operation.

Examine the DBA_LOCKS and DBA_WAITERS views to determine which sessions are blocking.

A good explanation is found in MetaLink note 15476.1, along with several scripts.

Also read the Concepts manual, as it goes into some detail on this. Data Concurrency and Consistency:
http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14220/consist.htm#g43931

HTH Jared

On 8/2/05, raja rao <raja4list_at_yahoo.com> wrote:
>
> Hi All,
> When i try to delete few rows (4 rows) from the table
> bom.cst_item_cost_details (oracle apps 11.5.9), i observed that the
> session is waitng on enqueues.
> (The above table is too big, it has 20 million records in it.)
> But could not get much info what is the child table on which it is
> serching.
> Can someone throw somelight how to understand and find the root cause of
> these enqueus.
> what even could help understand the root cause .
> Thanks,
> Raj
>
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-- 
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist

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