Re: does oracle use block level locking with RAC?

  • From: Yong Huang <yong321@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Sat, 10 May 2008 15:33:36 -0700 (PDT)

> 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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