General Properties for a Group

In the Group Properties dialog you identify the group with a name and comment and indicate how you want to handle indexes, constraints, and errors for all member subscriptions in the group. The properties that you can set depend on whether you are editing the properties of an existing group or creating a new group.

Group Name

If you are creating a new group using the Insert Group or Insert Incremental Group commands, enter up to 127 characters for the group name. After a group has been saved you must use the Rename command if you want to change the name of the group. If you are creating a new group from the Add Subscription Wizard you name the group in the New Group Name dialog and it cannot be changed in the Group Properties dialog.

Indexes/Constraints Options

If the source data for a snapshot subscription has indexes or constraints (primary or foreign key or reference constraints), you can choose whether to replicate those to the destination.

The Indexes/Constraints options allow you to specify whether you want to replicate all indexes and/or all constraints for all the subscriptions that are members of the group. Enabling the group setting overrides the settings for replicating specific indexes and constraints that are specified on the Indexes tab of the properties for each subscription.

For example, if the Indexes tab in the properties for a subscription is set to replicate any of the available indexes and constraints and you include that subscription as a member of a group that does not replicate all indexes or constraints, the indexes and constraints that are set to replicate for the subscription are automatically disabled. Likewise, if the subscription properties do not specify to replicate any of the indexes and constraints and you include the subscription as a member of a group that has the Replicate All Indexes and/or Replicate All Constraints options enabled, all the available indexes or constraints, respective to which group option is enabled, are automatically replicated.

Any of the changes to the indexes and constraints settings that are automatically applied to the member subscription as a result of changing the group property affect the properties of that subscription anywhere it appears, whether as an individual subscription under a specific source or as a member of another snapshot replication group.

For a subscription that performs incremental updates, you can choose whether to replicate indexes to the destination. The indexes are created only when the baseline replication occurs. If the indexes change at the source, the baseline must be re-synchronized. You cannot replicate foreign constraints, but you have an option of requiring SQDR to use a Relative Record Number or ROWID as a unique field for tracking change data from a Db2 for i or Oracle host. Enable the Force Use of RRN option to have all new subscriptions in the group use a RRN to help ensure the integrity of tables that do not have unique indexes or have columns that contain timestamps or other data types that do not map precisely from the source DBMS to the target DBMS. Setting the Force Use of RRN option adds a RRN column only for new subscriptions; it has no affect on existing subscriptions in the group.

The checkbox for Allow disable/enable indexes is related to the disableIndices service property (an advanced property that is accessed using the SQDR Properties application) but applies only to a specific group rather than the entire service.

If a subscription is defined as Use Existing, and the destination supports the functionality, setting this value to true will cause the existing non-unique indexes to be disabled prior to the baseline and will automatically re-enable the indexes after the baseline completes. This feature is available only for SQL Server and Oracle destinations and may improve baseline performance.  

Error Recovery Options

The error recovery options allow you to control how the group of subscriptions runs if there are errors or warnings encountered. A warning occurs if there is any truncation of data during a replication. An error indicates a problem that prevents replication of the data.  All errors and warnings are reflected in the replication statistics regardless of the error recovery option that is set for the group. The error recovery option only determines whether the group of subscriptions continues to run or whether the replication process is interrupted if a problem is encountered.

If you set the Error Recovery to Ignore Errors and Warnings, Data Replicator attempts to run every member subscription in the group even if an error or warning occurs. Selecting Halt on Errors Only stops the group replication with the subscription that encountered the problem, preventing any subsequent member subscriptions from running. Likewise, the Halt on Errors and Warnings setting prevents any subsequent member subscriptions from running if an error or a warning is encountered during replication of a subscription in the group.

If you set the group property to halt a group of snapshot replications if there is an error, or an error or warning, review the replication statistics to determine the error or warning that was encountered. After you correct the problem that caused the error or warning, you can select the member of the group that caused the replications to halt and then select the Run Group from this Point command to resume replicating the group of subscriptions. If a group of incremental subscriptions is halted due to an error, correct the error and then execute the Run Group command to run a new baseline replication for any subscriptions in the group that require it.

Maximum Retries (default 0) indicates the number of times running a group (typically a scheduled run) will retry a failing subscription.

Allow Checkpoint/Restart: Typically checkpoint restart has been used only for IR subscriptions. Setting this checkbox allows SQDR to checkpoint snapshot subscriptions for purposes of restart as well. This is useful when an incremental subscription is using a "manual" type of snapshot in conjunction with a set of snapshot subscriptions designed to partition the source select. Whether or not a specific subscription is restarted from the checkpoint is subject to other considerations (i.e. such as a useful "ordering" relationship).  See also the service property defaultAllowCheckpointRestart.

Concurrency Option

The value you specify for Maximum Subscriptions determines how many member subscriptions in the group can run at the same time. A value of 1 runs one subscription at a time, in succession, according to the Run Order shown for the group. The default value is to run a maximum of 5 subscriptions concurrently.

If the subscriptions in a group run concurrently, the order in which they complete depends on the length of time each subscription takes to run. For example, if there are 10 subscriptions in a group that has a Concurrency value of 3 and the first subscription takes hours to complete, the other subscriptions in the group may complete before the first subscription if they take only minutes to complete.