110 DBMS_MVIEW_STATS

DBMS_MVIEW_STATS package provides an interface to manage the collection and retention of statistics for materialized view refresh operations.

See Also:

Oracle Database Data Warehousing Guide for information about managing and using materialized view refresh statistics

This chapter contains the following topics:

110.1 DBMS_MVIEW_STATS Overview

You can use the procedures contained in the DBMS_MVIEW_STATS package to manage the collection and retention of statistics for materialized view refresh operations. This includes the level and granularity at which these statistics are collected and the duration for which they are retained in the database.

You can also set database level system defaults for the parameters that control statistics collection.

110.2 DBMS_MVIEW_STATS Security Model

Refer to the Usage Notes section in each subprogram for information about the privileges required to use the subprogram.

110.3 Summary of DBMS_MVIEW_STATS Subprograms

This table lists the DBMS_MVIEW_STATS subprograms and briefly describes them.

Table 110-1 DBMS_MVIEW_STATS Package Subprograms

Subprogram Description

PURGE_REFRESH_STATS Procedure

Purges the statistics of materialized view refresh operations that are older than the specified retention period.

SET_MVREF_STATS_PARAMS Procedure

Sets the values of parameters that define the collection level and retention period for materialized view refresh statistics. You can set the values either at the database level or for individual materialized views.

SET_SYSTEM_DEFAULT Procedure

Sets the system default value of a refresh statistics parameter. The two refresh statistics parameters are collection level and the retention period.

110.3.1 PURGE_REFRESH_STATS Procedure

This procedure purges refresh statistics that are older than the specified retention period for the specified materialized views.

This procedure forces a purge of refresh statistics without altering the retention period defined for the specified materialized views.

Syntax

DBMS_MVIEW_STATS.PURGE_REFRESH_STATISTICS (
		mv_list               IN     VARACHAR2,
		retention_period      IN     NUMBER);

Parameters

Table 110-2 PURGE_REFRESH_STATS Procedure Parameters

Parameter Description

mv_list

The fully-qualified name of an existing materialized view in the form of schema_name.mv_name. Use a comma-separated list to specify multiple materialized views.

Specify NULL to purge materialized view refresh statistics for all materialized views in the database.

retention_period

The number of days for which refresh statistics must be preserved in the data dictionary. Statistics for materialized view refresh operations that are older than the retention period are purged from the data dictionary.

The retention period specified in this procedure overrides the retention period that may have been set previously either at the database level or for specified materialized views.

Specify NULL to use the purging policy defined by the automatic statistics purge. Specify –1 to purge all refresh statistics.

Usage Notes

To invoke this procedure, you need either the SYSDBA privilege or privileges on every materialized view that is specified in mv_list.

110.3.2 SET_MVREF_STATS_PARAMS Procedure

This procedure sets the collection level and retention period for materialized view refresh statistics. You can set these properties either for individual materialized views or for all materialized views in the database.

Syntax

DBMS_MVIEW_STATS.SET_MVREF_STATS_PARAMS (
		mv_list            IN    VARACHAR2,
		collection_level   IN    VARCHAR2 DEFAULT NULL,
		retention_period   IN    NUMBER DEFAULT NULL);

Parameters

Table 110-3 SET_MVREF_STATS_PARAMS Procedure Parameters

Parameter Description

mv_list

The fully-qualified name of an existing materialized view in the form of schema_name.mv_name. Use a comma-separated list to specify multiple materialized views.

Specify NULL to set properties for all existing materialized views in the database.

collection_level

Specifies the level of detail used when collecting refresh statistics for the materialized views specified in mv_list.

Set one of the following values for collection_level:

  • NONE: No materialized view refresh statistics are collected.

  • TYPICAL: Only basic refresh statistics are collected and stored for the materialized views specified in mv_list.

  • ADVANCED: Detailed refresh statistics are collected and stored for materialized view specified in mv_list.

If this parameter is set to NULL, then the system default value for collection_level (set using SET_SYSTEM_DEFAULT) is used.

retention_period

Specifies the retention period, in days, for the refresh statistics of the materialized views specified in mv_list. Statistics that are older than the retention period are automatically purged from the data dictionary.

Valid values are between 1 and 1365000.

If this parameter is set to NULL, then the system default value for retention_period (set using SET_SYSTEM_DEAFULT) is used.

Set retention_period to -1 to specify that refresh statistics for the materialized views in mv_list must never be purged.

Usage Notes

To set the collection level or retention period of one or more materialized views, you must have privileges on those materialized views. To set the collection level or retention period for all materialized views in the database, you must have either the SYSDBA privilege or privileges on every materialized view in the database.

To set the system-level default values for statistics collection level and retention period, use the SET_SYSTEM_DEAFULT procedure.

Use the DBA_MVREF_STATS_PARAMS view to determine the currently-set retention period and collection level for materialized view statistics collection.

To disable refresh statistics collection for all materialized views in the database, use the following:

DBMS_MVIEW_STATS.SET_MVREF_STATS_PARAMS (NULL, ‘NONE’, NULL);

Note that the parameters set using SET_MVREF_STATS_PARAMS only affect materialized views that exist in the database at the time the procedure is run. Any new materialized views created after this procedure is run will use the system default values for collection_level and retention_period.

110.3.3 SET_SYSTEM_DEFAULT Procedure

This procedure sets system-wide defaults that manage the collection and retention of materialized view refresh statistics. All newly-created materialized views use these defaults until the parameters are reset explicitly using the SET_MVREF_STATS_PARAMS procedure.

Syntax

DBMS_MVIEW_STATS.SET_SYSTEM_DEFAULT (
		parameter_name	    IN   VARCHAR2,
		value             IN   VARCHAR2 DEFAULT NULL);

Parameters

Table 110-4 SET_SYSTEM_DEFAULT Procedure Parameters

Parameter Description

parameter_name

The name of the materialized view refresh statistics parameter whose system default value is being set.

The parameters that can be set are:

  • COLLECTION_LEVEL: Specifies the level of detail for collecting materialized view refresh statistics.

  • RETENTION_PERIOD: Specifies the duration, in days, for which refresh statistics are retained in the data dictionary

value

The value of the materialized view refresh statistics parameter.

The valid values for COLLECTION_LEVEL are:

  • NONE: No refresh statistics are collected for the refresh operation.

  • TYPICAL: Only basic refresh statistics are collected for the refresh operation. This is the default setting.

  • ADVANCED: Detailed refresh statistics are collected for the refresh operation.

The valid values for RETENTION_PERIOD are:

  • -1

  • Numbers between 1 and 1365000

The default value for retention_period is 31.

If you specify NULL for any of the parameters, then the system default setting for that parameter is used.

Usage Notes

You must have SYSDBA privilege to invoke this procedure.

Use the DBA_MVREF_STATS_SYS_DEFAULTS view to display the current default settings for materialized view refresh statistics collection.