Re: does oracle use block level locking with RAC?

From: Yong Huang <>
Date: Sat, 10 May 2008 15:33:36 -0700 (PDT)
Message-ID: <>

> I saw on a board somewhere that someone is having deadlock issues due to
> block level locking with Oracle RAC? I thought Oracle always did row level
> locking on everything? Could this be a mis-perception with something else?

Rick, I think you're concerned about transaction locks which are only at row level. If you're concerned about the locks that may cause deadlocks, whether they're simple transaction deadlocks (ORA-60) or others (e.g. ORA-4020, ORA-12829), there's an old document "Description of Oracle7 Wait Events and Enqueues" that describes most of the locks with a yes or no answer for "Deadlock Sensitive". Part of the document is in Note:75705.1. But both were written before many Oracle features were added.

I think buffer locks used to have an enqueue for it, BL. It's not deadlock sensitive. Now you can't even find it in v$lock_type. The concept of block level locking is sometimes brought up in literature about Oracle8i OPS, or XA transactions. I've never heard of a deadlock situation due to RAC buffer locking, or XA transactions.

Yong Huang

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Received on Sat May 10 2008 - 17:33:36 CDT

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