Re: How does Oracle support REPEATABLE READ

The only isolation levels supported in Oracle are READ COMMITTED (default) and SERIALIZABLE. Excerpt from the docs: SERIALIZABLE indicates that transactions in the session use the serializable

 transaction isolation mode as specified in SQL92. That is, if a serializable transaction

attempts to execute a DML statement that updates rows currently being updated by

another uncommitted transaction at the start of the serializable transaction, then the

DML statement fails. A serializable transaction can see its own updates.

READ COMMITTED indicates that transactions in the session will use the default

Oracle transaction behavior. Thus, if the transaction contains DML that requires row

locks held by another transaction, then the DML statement will wait until the row locks

are released.

-- 
Vladimir Zakharychev (bob@dpsp-yes.com)                http://www.dpsp-yes.com
Dynamic PSP(tm) - the first true RAD toolkit for Oracle-based internet applications.
All opinions are mine and do not necessarily go in line with those of my employer.


"Ben Brugman" <benbrugman_at_onbekend.nl> wrote in message news:3cc802e0.22565062_at_news.nl.uu.net...


> Our developers use Enterprise JavaBeans.

> Choosen isolation level is REPEATABLE READ.

> Does Oracle give this isolation level (or better)

> as described below ?

> (Text is taken from a standard JavaBeans book).

> 

> Thanks,

> Ben Brugman

> 

> Environment :

> Borland Enterprise Server.

> Oracle JDBC driver.

> 

> 

> From:  Mastering Enterprise JavaBeans.

> 

> "When to Use REPEATABLE READ

> Use REPEATABLE READ when you need to update one or more data elements

> in a resource, such as one or more records in a relational database.

> You want to read each of the rows that you're modifying and then be

> able to update each row, knowing that none of the rows are being

> modified by other concurrent transactions. If you choose to reread any

> of the rows at any time later in the transaction, you'd be guaranteed

> that the rows still have the same data that they did at the beginning

> of the transaction."

> 

> JDBC drivers should support the REPEATABLE READ isolation level.

> When using the Oracle JDBC driver will it support the REPEATABLE READ

> isolation level with the functionality as stated above? Especially the

> part : "knowing that none of the rows are being modified by other

> concurrent transactions" ?

> 

> 

> Side question: On which ORACLE isolation level is the JDBC REPATABLE

> READ isolation level mapped ?

> 

> Ben Brugman