Serialized transactions with database files - assure_mimix - 10.0

Assure MIMIX Administrator Reference

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Assure MIMIX™ Software
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Assure MIMIX
Assure MIMIX Administrator Reference
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A new data group created with the shipped default values will be configured for multithreaded database apply processing, which cannot serialize data area, data queue, and IFS object transactions with database file transactions. If you need to serialize transactions, you must configure data groups for single-threaded database apply processing or convert the resource groups to which the data groups belong to us single-threaded database apply processing.

In data groups that use single-threaded database apply processing, transactions completed for database files and objects (IFS objects, data areas, or data queues) can be serialized with one another when they are applied on the target system. If you require serialization, these objects and database files must share the same data group as well as the same database apply session, session A. For example, when a database record contains a reference to a corresponding stream file that is associated with the record, serialization may be desired.

For example, assume that a hotel uses a database application to reserve rooms. Within the application, a data area contains a counter to indicate the number of rooms reserved for a particular day and a database file contains detailed information about reservations. Each time a room is reserved, both the counter and the database file are updated. If these updates do not occur in the same order on the target system, the hotel risks reserving too many or too few rooms. When using system journal replication, serialization of these transactions cannot be guaranteed on the target system due to inherent differences in MIMIX processing from the user journal (database file) and the system journal (default for objects). With user journal processing, MIMIX serializes these transactions on the target system by updating both the file and the data area. Thus, as long as both the database file and data area are configured to be processed by the same apply session and processing of an object is not held due to an error, updates occur on the target system in the same order they were originally made on the source system.

Since MIMIX uses apply session A for all objects configured for user journal replication, serialization may require that you change the configuration for database files to ensure that they use the same apply session. Load balancing may also become a concern.