Thomas Kyte wrote:
> In article <41e401e2$1_2_at_127.0.0.1>, DA Morgan says...
>
>>casey.kirkpatrick_at_gmail.com wrote:
>>
>>
>>>This leads me to another thought - wouldn't it be nice if Oracle
>>>offered another token "UNLOCKED ONLY", to be used like:
>>>
>>>CURSOR C1_CUR IS
>>>SELECT * FROM T1
>>>WHERE <conditions>
>>>FOR UPDATE
>>>UNLOCKED ONLY;
>>>
>>>where "UNLOCKED ONLY" is like a sister command to "NOWAIT" which simply
>>>ignores any rows which cannot be acquired without a NOWAIT violation?
>>>Or would there be data integrity violations down that road?
>>
>>If I understand your intent it already exists.
>>
>>SELECT ...
>
>>FROM ...
>
>>WHERE ...
>>FOR UPDATE NOWAIT SKIP LOCKED;
>>
>>It was created, as I recall, as part of Advanced Replication, and is
>>not documented. Search the archives as Tom Kyte has posted some warnings
>>with respect to its use. I can't find them right now and don't want to
>>rely on my memory.
>
>
> it is for AQ (queues) and is dangerous in the wrong hands as it works for
> special cases of certain SQL statements only. Not documented.. the method the
> OP used (query the data's rowid, select for update by rowid) is the way to do it
> if you need this functionality.
Thanks for clarifying that it is AQ not AR.
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)
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Received on Tue Jan 11 2005 - 18:29:48 CST
