I want to make sure that when one client is updating the row, the others will be waiting, i.e. Thanks Yes, you will want to use their transactions, which will hook into an EJB Transaction if you already have one. SO, does that mean I have to use "locking" plus "transaction" ? You can however manually specify a pessimistic lock through Session.load() (with Lock Mode) Session.lock(), or Lock Mode() � in a DB like Oracle that will result in the use of "SELECT ... The creators of Hibernate feel that pessimistic locking does not scale well. Transactions And Concurrency Bear with me, I am sort of confused here --- What I need is to make sure that at any given time only one client can update the database, after it is done, the next one can update it...The first will be the latest version of your mappings. The second will be a set of versioned mapping fragments as described above. I have a basic question --- What if I need to frequently update my database or add/delete rows by using Hibernate ? Do I have to use Hibernate transaction feature for this ? It seems there are two issues going on here -- transaction and locking. do I have to put the 'update" operation inside a transaction ? from Mark's response, he didn't mention using any lock. I guess I should use one of the two locking mechanism.The following code snippet shows how easy it is: This example uses the spring Class Path Resource to load the mappings file from the classpath, and the Upgrade Task Connection Provider to inject a datasource into the process. What people usually do not realise is that the mappings files do not need to hold your entire schema.
I have been inspired by recent discussions on upgrade frameworks to show how hibernate can be used to provide simple incremental database schema maintenance.This feature, sometimes referred to as the ability to generate Data Definition Language (DDL) scripts, makes it possible (given a valid file) to create, update, and even drop tables in a target database.You can do this at runtime, during development, or via scripts generated for later use by a system administratoran invaluable capability if you expect to support multiple target databases (during either development or deployment) or have a high degree of database schema change.Situation I have a local H2 in memory database for integration tests and an Oracle db for production. The in memory H2 database is created automatically by adding The problem When creating the H2 database, Hibernate won't create the schema before creating tables.As a result it will show errors when trying to create the tables in non existing schema and fail in any query (queries will be run with sowa.business_operations). Schema Update] - Running hbm2ddl schema update 2011-01-18 ,885 INFO [org.hbm2ddl.Export is used to generate the schema from scratch; it is especially useful if the application is not allowed to directly execute DDL (because, say, a database administrator is expected to perform these tasks). Typically, this is used to address a situation in which an incremental update to an application requires a relatively minor change, such as a new property.Consider, for example, an application with a user object (and corresponding user table). You make the change to your file and the corresponding Java code, and now would like to reflect the change in the deployed database.Database schema maintenance is one of the more difficult aspects of upgrading applications, particularly when the application supports multiple databases, so I am very happy that hibernate helps out during upgrades.Hibernate provides a class called Schema Update that is able to synchronise a set of hibernate mappings with a database schema.Database Metadata] - table not found: business_operations 2011-01-18 ,941 ERROR [org.hbm2ddl.Schema Update] - Unsuccessful: create table sowa.business_operations 2011-01-18 ,942 ERROR [org.hbm2ddl.