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

> Having looked at M$'s implementation in my lab my impression is that

Please post your DDL and SQL so we can all take a look - thankyou.

In reality they have reengineered the way a lot of things work to use the Row Versioning code, online index creation/rebuild, triggers, transaction isolations.

-- 
Tony Rogerson
SQL Server MVP
http://sqlserverfaq.com - free video tutorials


"DA Morgan" <damorgan_at_psoug.org> wrote in message 
news:1140543201.747693_at_jetspin.drizzle.com...
> 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 ?).

>>

>> Just like Oracle never recommends bitmap indexes in OLTP..

>> So _barring_stupidity_ I'd guess that's correct.

>> I can't warrant for 160,000 IGS employees ;-)

>>

>>> And presumably you would advise MS users to not use UR as well ?

>>

>> Unless they can tolerate the implication. Just like I wouldn't recommend 

>> an Oracle customers snapshot isolation if their transaction must be 

>> serializable.

>>

>>> What is the default isolation level for DB2 LUW ?

>>

>> Cursor stability (aka read committed).

>> This is also by far the most popular isolation level on DB2.

>>

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

>> I have no clue. But apparently I'm on my way to becoming a SS2005 expert 

>> in no time in this group. ;-)

>>

>>>> 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 

>>> ?

>>

>> And here goes another twist. == Concurrency behavior <> implementation. 

>> Not even <> isolation level.

>>

>> SQL Server 2005, unless i'm gravely mistaken suppors two new twists.

>> One of them is MVRC, the other is last committed without readers blocking 

>> writers.

>> The point being made (at least as I understand it) is that SQL Server's 

>> IMPLEMENTATION of MVRC does not scale and is slow for unspecified reasons 

>> and that last committed is a bad isolation level BECAUSE of readers 

>> blocking writers.

>>

>> So.. is there any interest in bringing the debate back to a technical 

>> discussion?

>> Obviously I am not trolling for M$. I'm really interested on what folks 

>> perceive as the issue.

>>

>> Cheers

>> Serge

>
> 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)