Timesten - Database

> Database > (TimesTen|TT) (In-Memory Database|IMDB)

1 - About

A TimesTen database is a collection of elements such as:

  • tables,
  • views,
  • and sequences

that can be accessed and manipulated through SQL.

Each TimesTen database is created when the first connection initiates. The database instance is freed only when all existing connections have been disconnected.

The configuration for the TimesTen database is contained within the first connection attributes.

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3 - Persistence

You cannot change the permanent or temporary attribute on a database after it is created.

When a database is created, it has either the permanent or temporary attribute set

3.1 - Permanent

Permanent databases are stored to disk automatically through a procedure called checkpointing.

3.2 - Temporary

Temporary databases are not stored to disk. A temporary database is automatically destroyed when no applications are connected to it; that is, when the last connection disconnects or when there is a system or application failure. TimesTen removes all disk-based files when the last application disconnects.

A temporary database cannot be backed up or replicated. Temporary databases are never fully checkpointed to disk, although Checkpoint operations can have significant overhead for permanent databases, depending on database size and activity, but have very little impact for temporary databases. Checkpoints are still necessary to remove transaction log files.

However, temporary databases do have a transaction log, which is periodically written to disk, so transactions can be rolled back. The amount of data written to the transaction log for temporary databases is less than that written for permanent databases, allowing better performance for temporary databases. Recovery is never performed for temporary databases.

You can increase your performance with temporary databases. If you do not need to save the database to disk, you can save checkpoint overhead by creating a temporary database.