Product Documentation

Database Administrator's Guide

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Transaction Control Options

FairCom DB offers three modes of transaction processing logic:

  1. No Transaction Control.

    With no transaction control defined for a data file, read/write access to the file will be very quick. However, no guarantee of data integrity will be available through atomicity or automatic recovery.

  2. Preimage Transaction Control (PREIMG - partial) (atomicity only).

    If the PREIMG file mode is used, database access will still be fast, and some data integrity will be provided through atomicity. With atomicity only, (PREIMG), changes are made on an all or nothing basis, but no automatic recovery is provided.

  3. Full Transaction Control (TRNLOG - atomicity with automatic recovery).

    If your application files have been setup with the TRNLOG file mode, all the benefits of transaction processing will be available, including atomicity and automatic recovery. Automatic recovery is available with TRNLOG only, because TRNLOG is the only mode where all changes to the database are written immediately to transaction logs. The presence of the transaction log (history of changes to the files) allows the server to guarantee the integrity of these files in case of a catastrophic event, such as a power failure. Recovering files without a TRNLOG file mode from a catastrophic event will entail rebuilding the files. File rebuilding will not be able to recover data not flushed to disk prior to the catastrophic event.

Note: Atomicity and automatic recovery are defined in Glossary.

It is important for application developers to understand the complete aspects and consequences of any chosen transaction mode.