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Re: Database or store to handle 30 Mb/sec and 40,000 inserts/sec

From: Mark Townsend <markbtownsend_at_comcast.net>
Date: Mon, 20 Feb 2006 10:12:21 -0800
Message-ID: <43FA0685.7040900@comcast.net>


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 ? What is the default isolation level for SQL Server 2005 ?

> 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 ? Received on Mon Feb 20 2006 - 12:12:21 CST

Original text of this message

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