SQL/DataSynchronization Facility: Product Summary

The SQL/Data Synchronization Facility (SQL/DSF) assists DB2/VSE database administrators in managing distributed database environments. In such environments, it must be ensured that the distributed tables remain in a consistent state. The following SQL/DSF facilities help database administrators in achieving this goal:

Synchronization | Propagates changes performed on DB2/VSE tables to other databases.
Transfer | Transfers tables between different databases.
Compare | Compares tables in different databases.
Conditional transfer | Transfers a table to the target database, when a table compare results in mismatch.

All SQL/DSF functions are performed from the VSE/ESA DB2/VSE environment. They operate:

- on DB2/VSE databases
- on database platforms that can connect to DB2/VSE using DRDA

SQL/DSF functions can be invoked :

- using VSE JCL
- using the RULES of the SQL/DSF Synchronization Scheduler

TABLE SYNCHRONIZATION

Synchronization progagates table changes from a DB2/VSE source database to the target database, which can be another DB2/VSE or any other database platform that can connect to DB2/VSE. Synchronization is a cost-effective alternative for a complete table copy, as it applies only the INSERT, DELETE and UPDATE statements executed in the source database.

Data Capturing

Synchronization implies that the source table changes have been captured in the source database. The capturing function is performed by the SQL/Auditing Facility, a program product available from Software Product Research. All SQL statements, both dynamic and compiled, are captured, regardless of their origin.

Synchronization Method

The log of the SQL/Auditing Facility contains the full text of all SQL statements captured in the DB2/VSE server. Synchronization consists in executing these statements against the target database.

Synchronization Performance

> Since SQL/DSF uses the captured statement for synchronization and not the DB2/VSE log, an SQL statement that alters multiple rows will be synchronized in a single transaction.

> Synchronization User Exit

> If requested, SQL/DSF will invoke a user exit before applying the source statements to the target database. The exit can modify the statement text or take any other appropriate action.

TABLE TRANSFER

The transfer function copies all rows of a designated table to the target table in another database. At the user's choice, transfer will replace or append to the target. The transfer is performed using VSE subtasks: no disk or tape storage is required during the operation.

TABLE COMPARE

The function compares all rows of a named table with the table in the designated target database and prints the contents of the mismatching rows.

CONDITIONAL TABLE TRANSFER

The conditional transfer function is a combination of the compare and the transfer functions. A conditional transfer compares both tables and initiates a transfer when the compare results in a mismatch.

THE SQL/DSF SCHEDULER

SQL/DSF provides the SQLDSFS Scheduler program to assist an installation in setting up a DataSync Server environment. Using the Scheduler, most synchronization tasks can be automated. The Scheduler processes table synchronizations and transfers automatically and chronologically, as requested in its RULES file.