Installing > Installing a Development Environment > Completing postinstallation configuration tasks > Configuring the H2 database

Setting Multi-Version Concurrency Control (MVCC)

You can enable or disable Multi-Version Concurrency Control (MVCC). MVCC is enabled by default.

About this task

The MVCC feature allows higher concurrency than using exclusive table level or row level locks. When using MVCC in this database, delete, insert, and update operations only issue a shared lock on the table. An exclusive lock is still used when adding or removing columns, when dropping the table, and when using SELECT... FOR UPDATE. Connections only see committed data, and their own changes.

That means, if connection A updates a row but has not committed the change, connection B sees the old value. Only when the change from connection A is committed, the new value is visible to other connections (read committed). If multiple connections concurrently try to update the same row, the database waits until it can apply the change, but at most until the lock timeout expires.

Tasks

1. Edit the %CURAM%\EJBServer\project\properties\Bootstrap.properties file.

2. Specify true or false in the curam.db.h2.mvcc property. For example:

   # Property to disable MVCC. Default: true. (Optional)
   curam.db.h2.mvcc=false
   

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