Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #14255

Re: JDBC transaction isolation

Show all headers | View raw

On 5/3/2012 11:11 PM, Richard Maher wrote:
> On May 4, 10:34 am, Arne Vajhøj<a...@vajhoej.dk>  wrote:
>> On 5/3/2012 10:08 PM, Richard Maher wrote:
>>> On May 4, 7:57 am, Arne Vajhøj<a...@vajhoej.dk>    wrote:
>>>> On 5/3/2012 6:23 PM, Richard Maher wrote:
>
>>>>> Is anyone else of the opinion that Oracle really does not support the
>>>>> serializable isolation level? (At least not in the way that SQL Server, Rdb,
>>>>> and I'm sure others do) That is, it doesn't prevent inserts to the other
>>>>> txn's result-set,touched-rows by locking but rather fudges some sort of
>>>>> snapshot/consistent-view of old data. (And even then with restrictions)
>>>>> Eg: - select count(*) from employees where dept_code=1;
>>
>>>> Oracle use MVCC instead of locking.
>>
>>>> And that may seem to be cheating, but I believe it meet
>>>> the formal isolation level definitions.
>>
>>> Depends where you get your definition of "formal isolation
>>> definitions" I guess: -
>>
>>> -----------------------------------------
>>
>>> Definitive: -
>>
>>> http://msdn.microsoft.com/en-us/library/ms173763.aspx
>>
>> That is how SQLServer implements it.
>>
>> The definitive definition is in the SQL standard.
>>
>> It says that serilizable prevents:
>> * dirty reads
>> * non repeatable reads
>> * phantom reads
>
> Which ref/link are you using? "Neutral" Ask Tom? I'm interested in the
> exact pre-spun wording too.

http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt

>> Oracle meet that as all reads will return data as they were
>> at the start of the transaction.
>>
>
> Look, I don't know what Mark's expectations were when he chose to
> specify "isolation level serializable" but in reference to Table 7 at
> the bottom of: -
> http://www.oracle.com/technetwork/issue-archive/2005/05-nov/o65asktom-082389.html
>
> I suspect his business requirement may mandate that Session 2's
> "insert into b" be blocked until Session 1's txn commits/rollsback.
> Most modern, sophisticated databases are capable of meeting such
> requirements. Oracle is not.

Actually the trend seems to be that more and more databases
support MVCC.

> It's no use simply hiding the fact that someone else has just
> completely invalidated your SUM() or COUNT() or any other range
> retrievals and validation, updates, and business decisions will now
> based on those stale values!

Updates of stale values will fail.

Arne

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

JDBC transaction isolation markspace <-@.> - 2012-05-03 07:30 -0700
  Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 11:53 -0400
    Re: JDBC transaction isolation markspace <-@.> - 2012-05-03 11:43 -0700
      Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 15:00 -0400
        Re: JDBC transaction isolation Lew <lewbloch@gmail.com> - 2012-05-03 14:00 -0700
          Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 17:13 -0400
        Re: JDBC transaction isolation "Richard Maher" <maher_rj@hotspamnotmail.com> - 2012-05-04 06:23 +0800
          Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 19:57 -0400
            Re: JDBC transaction isolation Richard Maher <maherrj@googlemail.com> - 2012-05-03 19:08 -0700
              Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 22:34 -0400
                Re: JDBC transaction isolation Richard Maher <maherrj@googlemail.com> - 2012-05-03 20:11 -0700
                Re: JDBC transaction isolation Richard Maher <maherrj@googlemail.com> - 2012-05-03 22:33 -0700
                Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-04 08:27 -0400
                Re: JDBC transaction isolation Lew <lewbloch@gmail.com> - 2012-05-04 06:58 -0700
          Re: JDBC transaction isolation Lew <lewbloch@gmail.com> - 2012-05-03 17:15 -0700
            Re: JDBC transaction isolation Arne Vajhøj <arne@vajhoej.dk> - 2012-05-03 21:22 -0400
              Re: JDBC transaction isolation Lew <lewbloch@gmail.com> - 2012-05-03 18:32 -0700

csiph-web