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IUUC_REPAIR_REPL_CONTROL_CDC - Resolve Inconsistencies Identified by CDC Application

IUUC_REPAIR_REPL_CONTROL_CDC - Resolve Inconsistencies Identified by CDC Application

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Prerequisites

You have used the Cross-Database Comparison (CDC) application (an SAP Solution Manager application that compares the data consistency between systems) to analyze the source and target systems.

Purpose

When you use the Cross-Database Comparison application to analyze the source and target systems with regard to data consistency, the application can identify the inconsistencies outlined below.

In this report, you use this information to resolve these inconsistencies.

Inconsistency Identified Action Taken by SAP LT Replication Server
Objects exist in the source system, but not in the target system. SAP LT Replication Server inserts the missing rows in the target system
Objects exist in the target system but not in the source system. SAP LT Replication Server removes the rows from the target system.
Objects exist in both systems, but there are differences with regard to data. SAP LT Replication Server adjusts the values in the target system so that they are consistent with the values in the sender system.

Note

You can only resolve inconsistencies for tables that have the status In Replication.

Selection

In order to resolve the inconsistencies identified by the Cross-Database Comparison application, you must specify the following information:

Connection Information

You must specify an RFC connection from the LTR system to the CDC system. The system uses this RFC connection to identify the relevant mass transfer IDs, tables, CDC instances, and CDC runs.

Selection Criteria

You must specify the following information:

  • Mass Transfer ID
  • Table
You can only resolve inconsistencies for one table at a time. You must specify the relevant table. You can use the input help to select the tables that are associated with the mass transfer ID. Note that a table in this case corresponds to a CDC object.
  • Comparison Instance
  • Comparison Run

Runtime Options

Background Information

SAP LT Replication Server uses a logging table in the source system to record any changes to a table that is being replicated (by using sequence numbers and record keys). This ensures that the SAP LT Replication Server can replicate these changes to the target system.

In order to resolve an inconsistency, the system updates the logging table with the relevant record, and takes the relevant operation in the target system (INSERT, UPDATE, or DELETE). However, the following constraints apply:

  • If the record exists in the source table, only the operations INSERT and MODIFY are possible in the target system. The operation DELETE is not possible.
  • If the record does not exist in the source table, then only the operation DELETE is possible. The operations INSERT and MODIFY are not possible.

The logging table uses sequence numbers that make a record unique. The sequence number is incremented automatically, and the database records the current value. When SAP LT Replication Server resolves an inconsistency, the relevant record is entered in the logging table, and this involves the creation of a sequence number (these sequence numbers begins with '1').

In order to ensure that no conflicts occur with regard to the newly created sequence number and the existing sequence numbers, SAP LT Replication Server can take the following actions:

  • If the logging table is empty, SAP LT Replication Server ensures that the newly created sequence number is lower than the current sequence number assigned by the database.
  • If the logging table is not empty, SAP LT Replication Server ensures that the newly created sequence number is lower than the lowest sequence number for the records that were entered in the logging table as result of any change to an application table.

You can choose one of the following options:

  • Do Not Update Logging Table if Record Key Exists
Before the system updates the logging table (and makes any changes to the target system), the system can check whether any potential new inconsistencies might arise. To do this, the system checks whether an entry for the record key exists in the logging table. If the record key already exists in the logging table, SAP LT Replication Server does not update the logging table, and does not make any changes to the target system.
SAP LT Replication Server also ensures that any newly created sequence numbers are not in conflict, as described above.
Note that the checks associated with this option can take a considerable amount of time to run.

  • Update Logging Table Without Making any Checks
If you choose this option, then SAP LT Replication Server does not check whether the logging table contains the record key, and does not check whether the sequence number is in conflict with an existing sequence number. This means that the system updates the logging table with the relevant record, and implements the change required to resolve the inconsistency in the target system.
If you choose this option, we strongly recommend that no changes are made to the source system table when this report is running.

Viewing Application Logs

If any issues occur while trying to resolve an inconsistency, the system creates a log entry in the SAP LT Replication Server Cockpit(transaction LTRC). In the tab page Application Logs, you can view such messages.






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