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Posted to user@tuscany.apache.org by 彬邵 <sh...@gmail.com> on 2007/03/06 07:41:48 UTC
Question:What does the property "collision" and "managed" in a DAS Column config mean?
Hi all
As the title says, when should these properties set true?
Can anybody help?
Thanks!
Re: Question:What does the property "collision" and "managed" in a DAS Column config mean?
Posted by 彬邵 <sh...@gmail.com>.
Thanks very much!
Your answer is a great help to me.
2007/3/7, Kevin Williams <ke...@qwest.net>:
>
> Hello,
>
> The DAS provides the option to employ optimistic concurrency control
> (OCC) on updates to the database. You can read more about this concept
> here:
>
> http://wiki.apache.org/ws/Tuscany/TuscanyJava/DAS_Java_Overview/RDBDAS_Java_User_Guide
>
> The OCC documentation is weak but I will add to it soon. Basically,
> "collision" identifies a column to be used as part of an over qualified
> update statement to enforce OCC. "Managed" means that it is the
> responsibility of the DAS to change the value of the "collision" column.
> A typical usage is to allow the DAS to control the modification of the
> "collision" column rather that forcing the application to do it. When
> the DAS is managing the collision column then it will increment the
> value of the column before writing the row to the database.
>
> Test cases in org.apache.tuscany.das.rdb.test.OCCTests demonstrate these
> concepts.
>
> --Kevin
>
> 彬邵 wrote:
>
> > Hi all
> >
> > As the title says, when should these properties set true?
> >
> > Can anybody help?
> >
> > Thanks!
> >
>
>
>
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>
>
Re: Question:What does the property "collision" and "managed" in
a DAS Column config mean?
Posted by Kevin Williams <ke...@qwest.net>.
Hello,
The DAS provides the option to employ optimistic concurrency control
(OCC) on updates to the database. You can read more about this concept
here:
http://wiki.apache.org/ws/Tuscany/TuscanyJava/DAS_Java_Overview/RDBDAS_Java_User_Guide
The OCC documentation is weak but I will add to it soon. Basically,
"collision" identifies a column to be used as part of an over qualified
update statement to enforce OCC. "Managed" means that it is the
responsibility of the DAS to change the value of the "collision" column.
A typical usage is to allow the DAS to control the modification of the
"collision" column rather that forcing the application to do it. When
the DAS is managing the collision column then it will increment the
value of the column before writing the row to the database.
Test cases in org.apache.tuscany.das.rdb.test.OCCTests demonstrate these
concepts.
--Kevin
彬邵 wrote:
> Hi all
>
> As the title says, when should these properties set true?
>
> Can anybody help?
>
> Thanks!
>
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