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Serge Rielau wrote:
> Mark Townsend wrote:
>
>> Serge Rielau wrote: >> >>> Galen Boyer wrote: >>> >>>> On 19 Feb 2006, galen_boyer_at_yahoo.com wrote: >>>> >>>> >>>>> When would you ever want to read uncommitted records? >>> >>> >>> >>> Uncommitted read is just fine for anything statistical. >>> When mining a DSS or ODS system there is no need to get exact data. >>> Whether someone returned a pair of shoes or not is irrelevant for >>> trend analysis. >>> Does Oracle support query sampling? If so, there you go... >> >> >> >> So IBM never recommends UR for DB2 LUW except for situations where >> users can tolerate wrong results (i.e data sampling ?).
>> And presumably you would advise MS users to not use UR as well ?
>> What is the default isolation level for DB2 LUW ?
>>> I find it highly amusing how posters justify isolation levels based >>> on locking behavior. >>> Isolation is semantics, locking is implementation. >>> There are quite viable solutions for READ COMMITTED isolation level >>> which have the exactly same concurrency behavior as Oracle's >>> implementation of Snapshot Isolation. >> >> >> >> I'm sorry - but who's implementation of RC is the same as Oracle's MVRC ?
Having looked at M$'s implementation in my lab my impression is that they have bolted MVRC on using scratch tables and huge amounts of CPU just to be able to claim they can now do what they used to claim was an Oracle weakness.
The average SQL Server developer/DBA doesn't have the skill set required to understand and use it.
My impression is that it is there for marketing purposes only. No doubt they will have a checkbox on a page with three columns something like this:
SQL Server Oracle DB2 Tables Yes Yes Yes Indexes Yes Yes Yes MVRC Yes Yes No
Followed by some nonsense pretending they have equivalent functionality. Microsoft has never been about quality software ... rather quality marketing.
-- Daniel A. Morgan http://www.psoug.org damorgan_at_x.washington.edu (replace x with u to respond)Received on Tue Feb 21 2006 - 11:33:35 CST