This is a monthly segment in which Versant Object Technology touches upon some aspect of object databases. This month's tip focuses on Checkpoint Commits.

CHECKPOINT COMMITS

In the Versant ODBMS, when a commit is performed, all locks for objects in the front end client cache are released so that others can have access to the objects involved in the transaction. Moreover, the front end cache is "flushed" of the objects involved in the transaction. Sometimes you may desire to retain the locks on these objects for a subsequent transaction and retain these objects in the front-end cache. This is the concept of a checkpoint commit.

Checkpoint commit concepts are also endorsed by the http://www.odmg.org.

In Versant, checkpoint commits are performed by calling the checkpointcommit() method of the Distributed Object Manager (DOM) variable (or in Smalltalk by sending the checkpointCommit message to the ODBInterface class. Since Versant is a true object database at the object level, there are methods so you can simply checkpoint commit only a group of specific objects. This allows flexibility in deciding what objects need to be locked and retained in the subsequent transaction after a commit.

This concludes the Versant Tip of the Month series for this year. To all our customers around the world, we wish you happy holidays. See you next year.

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