• file: File-based persistence

• jdbc: JDBC-based persistence

Must be set to jdbc for enhanced broker clusters (imq.cluster.ha = true).

Any message exceeding this size will be stored in a separate file of its own.

• b: Bytes

• k: Kilobytes (1024 bytes)

• m: Megabytes (1024 × 1024 = 1,048,576 bytes)

An unsuffixed value is expressed in bytes.

• 1600: 1600 bytes

• 1600b: 1600 bytes

• 16k: 16 kilobytes (= 16,384 bytes)

• 16m: 16 megabytes (= 16,777,216 bytes)

Free files in excess of this limit will be deleted. The broker will create and delete additional files in excess of the limit as needed.

The higher the limit, the faster the broker can process persistent data.

The higher this value, the less disk space is required for the file pool, but the more overhead is needed to clean files during operation.

Setting this property to true saves disk space for the file store, but slows broker shutdown.

Setting this property to true eliminates data loss due to system crashes, but at a cost in performance.

Setting this property to true improves performance at the cost of increased memory usage. Set to false for file systems that do not support memory-mapped files.

Can improve performance if imq.persist.file.sync.enabled is true and the number of concurrent transactions being processed is high:

• If true, write operations to the transaction log are not handled by individual connection threads; instead, writes from connection threads are added to a transaction queue. The connection threads then wait until they are notified that the transactions have been logged. A separate thread periodically drains the transaction queue and writes it to the transaction log. When possible, this thread groups together multiple active transactions and writes them to the transaction log in a single operation. After the write completes, waiting client threads are notified.

• If false, write operations to the transaction log are handled by individual connection threads. Only one thread at a time is able to write to the log.

Overrides the behavior for persisting non-transacted messages (as defined by the imq.persist.file.sync.enabled property):

• If true, non-transacted messages are written to the transaction log before they are written to the persistent store.

• If false, non-transacted messages are written directly to the persistent store.

Overrides the behavior for persisting non-transacted message acknowledgements (as defined by the imq.persist.file.sync.enabled property):

• If true, acknowledgements of non-transacted messages are written to the transaction log before they are written to the persistent store.

• If false, acknowledgements of non-transacted messages are written directly to the persistent store.

• derby: Java DB (Oracle Corporation)

• oracle: Oracle (Oracle Corporation)

• mysql: MySQL (Oracle Corporation)

• postgresql: postgreSQL

When true, the pool manager operates as follows:

• When closing unnecessary database connections at each imq.persist.jdbc.connection.reaptime interval, the pool manager destroys any connections in the pool that have been idle for a period longer than imq.persist.jdbc.connection.reaptime seconds, and attempts to replace them with new connections.

• When getting a connection from the pool, the pool manager destroys the connection if it has been idle for a period longer than imq.persist.jdbc.connection.reaptime seconds and replaces it with a new connection.

Normally, the pool manager validates a connection it gets from the pool by checking whether the connection is closed and, if possible, by checking whether a connection error has occurred on the connection.

When this property is set to true, the pool manager performs these additional validation checks:

• For JDBC 4 connections, check whether the connection is valid.

• Make the validation query specified by imq.persist.jdbc.connection.validationQuery on the connection.

Regardless of the value of this property, Message Queue relies on the underlying JDBC driver to return a good connection when it needs to create a new connection through the driver. Therefore, you should set imq.persist.jdbc.vendorName.driver to a vendor JDBC driver that performs connection retries when creating a new connection to the database server; for example, a ConnectionPoolDataSource.

This property is deprecated and may become unsupported in a future release of Message Queue.

Applicable when driver is used to connect to database.

Applies for embedded database, such as Java DB.

Applies for some embedded databases, such as Java DB.

For security reasons, the value can instead be specified using command line options imqbrokerd -dbuser and imqdbmgr -u.

If true, the imqbrokerd and imqdbmgr commands will prompt for a password, unless you use the -passfile option to specify a password file containing it.