Transaction Logging

TimesTen maintains a transaction log for each database to track all updates made within each transaction, so that those updates can be undone if the transaction is rolled back.

TimesTen recovers transactions using both the most recent checkpoint file and the most recent transaction log, which was written from the time of the last checkpoint operation after a system failure.

A transaction log record is created for each database modification, commit, and rollback. However, transaction log records are not generated for read-only transactions. Log records are first written to the transaction log buffer, which resides in the same shared memory segment as the database. The contents of the log buffer are then subsequently flushed to the latest transaction log file.

The transaction log is a logically ordered sequence of transaction log records, but physically consists of a set of one or more transaction log files and the in-memory log buffer within the TimesTen database. This log is shared by all concurrent connections.

The following sections describe how to manage and monitor the transaction log buffers and file:

• Managing Transaction Log Buffers and Files

• Using NFS-Mounted Systems for Checkpoint and Transaction Log Files

• Monitoring Accumulation of Transaction Log Files