Re: Locking - on a DB-Level

[Thomas Mahler]

Hi Martin,

[EMAIL PROTECTED] wrote:

Hi,
Is it possible to get a lock on a DB-Level, like a "select for update" on
Oracle?
The Lock you can obtain seems just to work inside memory and not on a
DB-Level.

The OJB ODMG pessimistic locking does not use DB-Level locking. You can use an in-memory version that only works within one VM. But you can also use the PersistentLockManager that can manage multiple VMs (even accross different physical machines). You can set this up in OJB.properties.

We don't use DB-Level locking as it is implemented differently on different RDBMS platforms. Some databases (e.g. DB2) cannot even guarantee row-level locking, but have lock escalations to page or even table level!

There is no way to *implicitely* use "select for update".
But you can ask OJB for a JDBC connection and perform it *explicitely* if needed.

cheers,
Thomas

thanks in advance

PS: working with ODMG on jakarta-ojb-0.9.7.






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