Hi,

we are using version for optimistic locking and we don't want any database (ORACLE) lock on the row when a new row is inserted

When we used EJBs, we didn't have lock on the row, now we have a row lock when using Hibernate

Is there an Hibernate configuration to avoid this database row-lock when we're doing an INSERT ?


Best regards,

Fabrice

Might be worth looking at the VERY detailed chapter in"Hibernate in Action" about isolation levels and transactions.

By the way, how can you ever have a row lock on a row you are inserting ?

Thx for your answer paul,



We are using P6Spy to trace the SQL requests and we have the following sequence :

Thread A inserts row1

Thread B inserts row2

Thread A inserts row2 .....waiting

Thread B inserts row1 .....deadlock


We don't want any waiting lock, when the threadA will try to insert row2, a violation integrity must be raised

I read again this chapter, we are using versionning + read commited , does this strategy prevent me for any row lock from Oracle ?

I think you are mistaken. INSERTs never block other INSERTs, especially not in read committed.

I have seen scenarios in which the whole file is locked, not in Hibernate but with EJB's. Of course in the normal state of affairs, a locked row on an insert makes no sense at all.

It could be that someone thinks they are using Read Uncomitted, but are actually using another level.

On the iSeries version of DB2 you can find out what isolation level you are actually using by setting the "trace" property to be "true" on the JDBC driver, who knows what the equivalent is on Oracle.

Thinking about it, doesn't Oracle use a file to provide surrogate identity fields ? Maybe that is what is getting locked, as obviously this would be updated whenever an insert takes placce.

It seems to be more of a db than a Hibernate question.

Thx for your answers,

I made some test Weblogic/EntityEjb with its optimistic concurrency and Weblogic/Hibernate, also with its optimistic concurrency

I looked at the system oracle table for locks reporting, V_$lock and i have the following results :

- With Entity Ejb : some DML locks are : LMODE = 2 (Row share)

- With Hibernate : all DML locks are : LMODE = 3 (Exclusive)

Does it mean that Weblo/Entity modifies the default Oracle lock policy ?

Can i do this with Hibernate ?


Fabrice,

Check your JDBC transaction isolation level.