Managing Database Properties

There are two types of database properties: monitorable and configurable.

Both monitorable and configurable properties can be further divided into properties having database-wide scope or instance-specific scope.

  • Monitorable property values can be viewed only when the associated database is enabled.

    Monitorable properties allow you to view run-time information related to databases, but you cannot change the values of these properties.

  • Configurable property values can be viewed and dynamically updated.

    Configurable properties affect the operation or configuration of the broker. You can change the value of these properties using DGMGRL or Cloud Control. You can edit properties whether the configuration and its members are enabled or disabled. However, if a configuration member is disabled, then the new property value does not take effect until you enable the configuration or member, as appropriate.

    See Also:

    Oracle Data Guard Broker Properties for a detailed list of all database properties

To see these properties, you can use the DGMGRL SHOW command or Edit Properties page in Cloud Control. Example 4-1 uses the SHOW DATABASE VERBOSE command to display information about the North_Sales database.

See Also:

Oracle Data Guard Command-Line Interface Reference for complete information about the DGMGRL command-line interface

Example 4-1 Using the SHOW DATABASE VERBOSE Command to Display Properties

DGMGRL> SHOW DATABASE VERBOSE 'North_Sales';

Database - North_Sales

  Role:                PRIMARY
  Intended State:      TRANSPORT-ON
  Redo Rate:           202 Byte/s  in 15 seconds (computed 11 seconds ago) 
  Instance(s):
    NorthSales

  Properties:
    AlternateLocation               = ''
    ApplyInstanceTimeout            = '0'
    ApplyInstances                  = '0'
    ApplyLagThreshold               = '30'
    ApplyParallel                   = 'AUTO'
    ArchiveLocation                 = ''
    Binding                         = 'OPTIONAL'
    DGConnectIdentifier             = 'north_sales'
    DelayMins                       = '0'
    FastStartFailoverTarget         = ''
    HostName                        = 'sales1'
    InconsistentLogXptProps         = '(monitor)'
    LogShipping                     = 'ON'
    LogXptMode                      = 'ASYNC'
    LogXptStatus                    = '(monitor)'
    MaxFailure                      = '0'
    NetTimeout                      = '30'
    ObserverConnectIdentifier       = ''
    PreferredApplyInstance          = ''
    PreferredObserverHosts          = ''
    RecvQEntries                    = '(monitor)'
    RedoCompression                 = 'DISABLE'
    RedoRoutes                      = ''
    ReopenSecs                      = '300'
    SendQEntries                    = '(monitor)'
    SidName                         = '(monitor)'
    StandbyAlternateLocation        = ''
    StandbyArchiveLocation          = ''
    StaticConnectIdentifier         = '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=sales1.example.com)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=North_Sales_DGMGRL.example.com)(INSTANCE_NAME=NorthSales)(SERVER=DEDICATED)))'
    TopWaitEvents                   = '(monitor)'
    TransportDisconnectedThreshold  = '30'
    TransportLagThreshold           = '30'

  Log file locations:
    Alert log               : /sales/oracle/diag/rdbms/north_sales/NorthSales/trace/alert_NorthSales.log
    Data Guard Broker log   : /sales/oracle/diag/rdbms/north_sales/NorthSales/trace/drcNorthSales.log

Database Status:
SUCCESS

Monitorable (Read-Only) Properties

Monitorable properties allow you to view information related to a configuration member, but you cannot change the property values.

Monitorable properties can be very helpful when you are trying to diagnose problems in the broker configuration. For example, you can view the InconsistentLogXptProps monitorable property to determine where there is a discrepancy in redo transport services properties between the broker configuration file and the actual value currently used by the database.

You can list all monitorable properties using the DGMGRL SHOW DATABASE VERBOSE command. Use the SHOW DATABASE command to obtain more details about a particular property. For example, the following shows the InconsistentLogXptProps property: 

DGMGRL> SHOW DATABASE 'North_Sales' 'InconsistentLogXptProps';

INCONSISTENT LOG TRANSPORT PROPERTIES

   INSTANCE_NAME         STANDBY_NAME        PROPERTY_NAME         MEMORY_VALUE         BROKER_VALUE 
      NorthSales          South_Sales            DelayMins                   10                    0

Cloud Control displays the information obtained from these properties on the Edit Properties page.

Configurable (Changeable) Properties

Configurable properties affect the operation or configuration of a database or far sync instance.

When you use DGMGRL or Cloud Control to create a primary database and import existing standby databases and far sync instances into a new broker configuration, the property values are initially imported from the database or far sync instance settings.

You can update many property values when a configuration member is either disabled or enabled. When a new member is added into the configuration, the broker connects to that member and imports initial values for the member's properties from the current member settings. For example:

DGMGRL> SHOW DATABASE 'North_Sales' LogXptMode;
  LogXptMode = ASYNC

DGMGRL> EDIT DATABASE 'North_Sales' SET PROPERTY LogXptMode='SYNC';
  Property "LogXptMode" updated

DGMGRL> SHOW DATABASE 'North_Sales' LogXptMode;
  LogXptMode = SYNC

When the configuration is enabled, for properties related to redo transport, the broker keeps the member property values in the broker configuration file consistent with the values being used by the member. The broker no longer maintains values for properties related to initialization parameters in the configuration file. Note that there is no issue with maintaining consistency. Although the broker no longer maintains values for these properties, it is still possible to use the broker CLI to update and examine the value of these properties. Due to user action, it is possible for the parameter value in the system global area (SGA) to differ from the parameter value in the server parameter file. This is not flagged as an inconsistency and only means that the server parameter file value will take effect the next time the database is restarted. The specified database must be accessible to be able to make these property changes.

Note:

Even though you can change a property value when the configuration is disabled, the change does not take effect on the configuration member unless the configuration is enabled. Also note that some property values can only be changed in the disabled state.

Resetting Broker Configurable Properties to Default Values

Most broker configurable properties have a default value, but you can specify a different value to override it.

The broker recognizes when a default value has been restored for a property and no longer considers it a user-supplied value. This is expedient in upgrade scenarios because if a default value for a property changes between releases, then the new default value is automatically put into effect after an upgrade is complete. Values that are considered user-supplied are not automatically upgraded.

You do not need to know the actual default value in order to reset it. You can reset a default value at the configuration, configuration member, or instance level.

See Also: