Transaction and Message Logs

Manage the size of the transaction and message logs to conserve disk space.

The transaction log file contains recovery and auditing information. Place the transaction log on a separate device or partition from the database itself to avoid database file fragmentation and to protect against media failure.

The transaction log can consume a large amount of disk space over time. Truncate the transaction log periodically to conserve disk space.

To truncate the log:
  1. Shut down the server.
  2. Start the server with the –m parameter as part of the start_iq command or .cfg file.
  3. Shut down and restart the server without the –m parameter.
Do not leave the –m switch permanently set. When –m is set, there is no protection against media failure on the device that contains the database files. Remove the –m from the .cfg after you restart the server. To move or rename the transaction log file, use the transaction log utility (dblog).
Warning!   The SAP Sybase IQ transaction log file is different from most relational database transaction log files. If for some reason you lose your database files, then you lose your database (unless it is the log file that is lost). However, if you have an appropriate backup, then you can reload the database.

Message Log

SAP Sybase IQ logs all messages in the message log file, including error, status, and insert notification messages. Limit the size of this file to conserve disk space.

At some sites the message log file tends to grow rapidly. To limit the size of this file:

  • Set a maximum file size and archive the log files when the active message log is full

  • Increase NOTIFY_MODULUS database option setting

  • Use the NOTIFY parameter to turn off notification messages in LOAD TABLE. INSERT, and CREATE INDEX statements

  • Use -iqmsgsz switch to limit the size of the message log

Additional Information

  • Utility Guide > start_iq Database Server Startup Utility > start_iq Server Options > -iqmsgsz iqsrv16 Server Option

  • Utility Guide > start_iq Database Server Startup Utility > start_iq Server Options > -m iqsrv16 Server Option

  • Reference: Statements and Options > Database Options > Alphabetical List of Options > NOTIFY_MODULUS Option

  • Reference: Statements and Options > SQL Statements > CREATE INDEX Statement

  • Reference: Statements and Options > SQL Statements > INSERT Statement

  • Reference: Statements and Options > SQL Statements > LOAD Statement

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Parent topic: Balancing Input/Output
Related concepts
Raw Devices
Disk Striping
Internal Striping
Random and Sequential File Access