Configuring and enabling Auto Update Statistics

  1. On the menu for the HCL OpenAdmin Tool (OAT) for Informix®, click Server Administration > Auto Update Statistics > Config.
  2. Based on your system performance and requirements, determine whether the default values are valid for your system.
    1. To specify the maximum time between statistics rebuilds, enter the number of days for the AUS_AGE parameter, such as 30, 60, or 90.
    2. To specify what percent of change to a table initiates a statistics rebuild, enter a percentage number, such as 20 or 50 for the AUS_CHANGE parameter.
    3. To specify whether AUS uses the recommended guideline rules, select On or Off from the list for the AUS_AUTO_RULES parameter. The default is On.
    4. To specify the number of rows below which statistics are always rebuilt, enter a number for the AUS_SMALL_TABLES parameter. The default is 100.
    5. To specify the PDQ priority, enter a number from -1 to 100 for the AUS_PDQ parameter. The default is 10. The Parallel Database Queries (PDQ) priority is one of the factors that determines how the database server uses resources for parallel processing.
    6. To specify the number of threads to use to run the update statistics tasks, enter a number of threads. OAT submits this number of AUS tasks to the Task Scheduler. This option requires HCL Informix version 11.70.
  3. Click Save to keep your changes.
  4. To determine whether the AUS tasks are enabled, click the Info tab and then click these tasks:
    • Auto Update Statistics Evaluation
    • Auto Update Statistics Refresh
      Note: If there is no work for the Auto Update Statistics Refresh task to do, the task disables itself. The next time the Auto Update Statistics Evaluation task runs, and creates work for the refresh task, the evaluation task automatically enables the refresh task.
    The Task Details page is displayed.
  5. Scroll down to the Enable Task field and ensure that it is selected.
  6. Specify how often the tasks are run with the fields that set the run window. Because AUS is a resource-intensive operation, a specific run window can be defined. The run window definition includes a start time and end time, and the days of the week to run. By default the run time window is 1:00 a.m. – 5:00 a.m. daily.
  7. Click Save to save any changes.

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