JDBC Type 2 Driver Programmer's Reference for SQL/MX Release 3.2.1 (H06.26+, J06.15+)

For example, using the mploc property in the OSS environment, specify the mploc property

including the prefix in either of the following forms:

-Djdbcmx.mploc=[\\node.]\$volume.subvolume

-Djdbcmx.mploc='[\node.]$volume.subvolume'

Transactions

The JDBC/MX driver provides transaction support to maintain data integrity and consistency. To

allow the application to interleave transactions between SQL/MX objects and the traditional file

system, the JDBC/MX driver checks if a transaction is active whenever it needs to interact with

SQL/MX.

The “transactionMode Property” (page 29) determines transaction processing behavior. If you use

transactionMode in a typical environment, with the default value mixed,

• When an active transaction exists, the autocommit setting is ignored, and the JDBC/MX driver

lets the application manage the transaction.

• When no active transaction exists, the JDBC/MX driver manages the transactions.

This implementation differs from JDBC/MP. In the JDBC/MP driver, two different types of URLs

decide which component manages the transaction.

If you are accessing BLOB and CLOB data, see also “Transactions Involving Blob and Clob Access”

(page 52).

Autocommit Mode and Transaction Boundaries

When JDBC/MX manages the transactions, the driver decides to start a new transaction. A new

transaction is started when no transaction is associated with the Connection. When there is a

transaction associated with the Connection, that transaction is resumed. The Connection

attribute autocommit specifies when to end the transaction. Enabling autocommit causes the

JDBC/MX driver to end the transaction in accordance with the following rules:

• The JDBC/MX driver rolls back the transaction for any SQL error in SQL statements other than

SELECT statements.

• In the case of non-SELECT SQL statements, the JDBC/MX driver commits the transaction if the

current transaction was started for this SQL statement.

• In the case of SELECT statements, the JDBC/MX driver commits the transaction at the time of

closing the result set.

• In the case of concurrent multiple SELECT statements, the JDBC/MX driver commits the

transaction only when the result set of the SELECT statement or the statement that started the

transaction is closed.

Disabling Autocommit Mode

When the autocommit mode is disabled, the application must explicitly commit or roll back each

transaction by calling the Connection methods commit and rollback, respectively. When

any SQL error occurs in SQL statements other than SELECT statement, SQL/MX flags the transactions

for aborting. In such a case, the transaction is rolled back without regard to whether the application

commits or rolls back the transaction.

The default is for auto-commit mode to be enabled when the Connection object is created. If the

value of auto-commit is changed in the middle of a transaction, the current transaction is committed.

If setAutoCommit is called and the value for auto commit is not changed from its current value,

it is treated as a NO-OP.

Transactions 33