# derby.storage.indexStats.auto

The derby.storage.indexStats.auto property, if set to true (the default), specifies that outdated index cardinality statistics are updated automatically during query compilation.

The query compiler schedules a job that updates the statistics in a separate thread.

The thread that updates the statistics in the background may affect the performance of the user threads. If this causes problems, you can set derby.storage.indexStats.auto to false.

To diagnose problems with automatic updating of index statistics, an application can set the property derby.storage.indexStats.log to true. The derby.storage.indexStats.trace property can be used to provide more detailed information.

For more information about index statistics, see "Working with cardinality statistics" in Tuning Derby.

## Default

True.

## Example

    -- system-wide property
    derby.storage.indexStats.auto=false

    -- database-level property
    CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(
        'derby.storage.indexStats.auto', 'false')

## Dynamic or static

Static. For system-wide properties, you must reboot Derby for the change to take effect. For database-wide properties, you must reboot the database for the change to take effect.

Parent topic: Derby properties
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