Chapter 2. Enabling Transactions
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## Chapter 2. Enabling Transactions

In order to use transactions with your application, you must turn them on. To do this you must:

- Turn on transactions for your environment. You do this by using the `EnvironmentConfig.setTransactional()` method, or by using the `je.env.isTransactional` `je.properties` parameter.

- Transaction-enable your databases. You do this by using the `DatabaseConfig.setTransactional()` method, and then opening the database from within a transaction. Note that the common practice is for auto commit to be used to transaction-protect the database open. To use auto-commit, you must still enable transactions as described here, but you do not have to explicitly use a transaction when you open your database. An example of this is given in the next section.

## Opening a Transactional Environment and Database

To enable transactions for your environment, you must initialize the transactional subsystem:

    package je.txn;

    import com.sleepycat.je.DatabaseException;
    import com.sleepycat.je.Environment;
    import com.sleepycat.je.EnvironmentConfig;

    import java.io.File;

    ...

    Environment myEnv = null;
    try {
        EnvironmentConfig myEnvConfig = new EnvironmentConfig();
        myEnvConfig.setTransactional(true);

        myEnv = new Environment(new File("/my/env/home"),
                                  myEnvConfig);

    } catch (DatabaseException de) {
        // Exception handling goes here
    }

You then create and open your database(s) as you would for a non-transactional system. The only difference is that you must set `DatabaseConfig.setTransactional()` to `true`. Note that your database open must be transactional-protected. However, if you do not give the `openDatabase()` method a transaction handle, then the open is automatically protected using auto commit. Typically auto commit is used for this purpose. For example:

    package je.txn;

    import com.sleepycat.je.Database;
    import com.sleepycat.je.DatabaseConfig;
    import com.sleepycat.je.DatabaseException;
    import com.sleepycat.je.Environment;
    import com.sleepycat.je.EnvironmentConfig;

    import java.io.File;

    ...

    Database myDatabase = null;
    Environment myEnv = null;
    try {
        EnvironmentConfig myEnvConfig = new EnvironmentConfig();
        myEnvConfig.setTransactional(true);
        myEnv = new Environment(new File("/my/env/home"),
                                  myEnvConfig);

        // Open the database. Create it if it does not already exist.
        DatabaseConfig dbConfig = new DatabaseConfig();
        dbConfig.setTransactional(true);
        myDatabase = myEnv.openDatabase(null,
                                        "sampleDatabase",
                                        dbConfig);

    } catch (DatabaseException de) {
        // Exception handling goes here
    }

### Note

Never close a database that has active transactions. Make sure all transactions are resolved (either committed or aborted) before closing the database.

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