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Home -> Community -> Mailing Lists -> Oracle-L -> Re: RE: oracle or mssql
Disagree.
"row-level" locking in SQL Server was introduced in some capacity only in
SQL Server 7 (not long time ago).
Before, it was "block-level" locking, and I saw lots of problems with that.
It's not the length of the single statement (select/update/...) that
matters. It's the length of the transaction, that causes a problem, if
"block_level" locking is used (and could be automatically escalated to
"extent" or even "table" level lock).
Igor Neyman, OCP DBA
ineyman_at_perceptron.com
> I don't see it as a gotcha, I've worked with SQL Server for almost 6 years
> on some pretty big databases and have never had a problem.
>
> At the end of the day, locking is at the row level, locks are held for a
> very short time (unless developers don't know what they are doing). A read
> will take a shared row level lock for a sub-second period of time
> (potentially), if your update is blocked for 0.2 seconds are you going to
> notice ? You have to realise that with row level locking the scope for
> blocking is minimal.
>
> Ade
>
> -----Original Message-----
> Sent: 31 October 2002 14:04
> To: Multiple recipients of list ORACLE-L
>
>
>
> But this default mssql behaviour is the performance 'gotcha' where readers
> block writers and writers block readers isn't it?
>
>
> Mike.
>
> -----Original Message-----
> Sent: 31 October 2002 09:12
> To: Multiple recipients of list ORACLE-L
>
>
> 'Dirty reads' in SQL Server means that you can view records that have not
> been committed. This is implemented by setting the TRANSACTION ISOLATION
> LEVEL to READ UNCOMMITTED.
>
> This is not default behaviour in SQL Server, the default TIL is READ
> COMMITTED (for very good reason). I can think of very few situations where
> you would want to see uncommitted records.
>
> Dirty blocks in SQL Server/Oracle are the same thing ie. a block/page in
> cache that has been changed but not flushed to disk.
>
> Ade
>
> -----Original Message-----
> Sent: 30 October 2002 18:43
> To: Multiple recipients of list ORACLE-L
>
>
> It sounds like he is saying that, once an "insert, update or delete"
> statement has been issued (without a following commit), then the records
> acted upon are now considered "dirty" - i.e. needing writing to disk.
>
> this is, of course, NOT what Oracle considers a dirty block.
>
> I agree with you, Jared!
>
> Tom Mercadante
> Oracle Certified Professional
>
>
> -----Original Message-----
> Sent: Wednesday, October 30, 2002 1:21 PM
> To: Multiple recipients of list ORACLE-L
>
>
> At least one of us has the incorrect understanding of 'dirty' reads,
> or I am taking you too literally, or something.
>
> What are you really saying?
>
> Oracle does not allow dirty reads.
>
> All queries are consistent to a point in time, the beginning
> of a transaction, whether implicit (select) or explicit ( start
> transaction ).
>
> SQL Server and Sybase do not guarantee this.
>
> The 'dirty' reads you are speaking of sound more to me
> like sloppy programming.
>
> Is that what you're referring to?
>
> Jared
>
>
>
>
>
>
> "Yechiel Adar" <adar76_at_inter.net.il>
> Sent by: root_at_fatcity.com
> 10/30/2002 08:54 AM
> Please respond to ORACLE-L
>
>
> To: Multiple recipients of list ORACLE-L
<ORACLE-L_at_fatcity.com>
> cc:
> Subject: Re: RE: oracle or mssql
>
>
> I would like to point out that what you call "dirty reads" are mostly
> the correct reads. Oracle method IS the dirty read.
>
> I am sure that your users does at least 1000 commits to every rollback.
> So when oracle gives you the data it already knows that this data is
> wrong. If you do the query again a minute later you will get new results
> that were available when you did the original query but were committed
> later. So you get a 1000/1 chance to get incorrect data.
>
> The "dirty read" method, on the other hand, gives you the current values,
> believing that they will be committed in a moment. So you get 1/1000
> chance
> to get wrong data.
>
> Which odds will you bet on?
>
> Yechiel Adar
> Mehish
> ----- Original Message -----
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Sent: Tuesday, October 29, 2002 2:18 PM
>
>
> List,
> I'm always keen to refresh on database comparisons so thanks for
> everyone's pointers.
>
> I'm surprised Oracle doesn't make more of an issue about their locking and
> concurrency methods (i.e. redo/rollback/undo).
>
> MSSQL seems to deal with it in two ways:
> Default: readers and writers prevent writers from accessing data until
> they
> are finished with it!
> Other method: no control, you just get dirty reads!
>
> Anyone got anything to add to this? Or am I wrong?
>
> - Mike.
>
>
> -----Original Message-----
> Sent: 24 October 2002 17:29
> To: Multiple recipients of list ORACLE-L
>
>
> As I said, use mssql ONLY if your boss is willing to be strapped into a
> MicroSlop only platform. If he's even remotely thinking of using a
> different OS
> then you can't use mssql.
>
> Dick Goulet
>
> ____________________Reply Separator____________________
> Author: GKor_at_rdw.nl
> Date: 10/23/2002 11:48 PM
>
> goodmorning
> everybody who responded to my basic question : thanks
>
> summary
>
> professional : use oracle enterprise edition
> semi professional : use oracle standard edition / mssql enterprise edition
> in all other cases mssql standard edition
>
>
>
> > -----Oorspronkelijk bericht-----
> > Van: Mohammad Rafiq [SMTP:rafiq9857_at_hotmail.com]
> > Verzonden: woensdag 23 oktober 2002 20:51
> > Aan: Multiple recipients of list ORACLE-L
> > Onderwerp: RE: oracle or mssql
> >
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Jenner Mike
> INET: M.Jenner_at_southampton.gov.uk
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Igor Neyman INET: ineyman_at_perceptron.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu Oct 31 2002 - 11:19:47 CST
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