Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

Distributed Oracle Data Warehouses
Data Integrity And Distributed Databases

Data integrity refers to the ability of a distributed Oracle warehouse to manage concurrent updates to data in many physical locations while ensuring that all of the data is physically and logically correct. While data integrity is managed very effectively within a single database with row locking, deadlock detection, and roll-back features, distributed data integrity is far more complex. Recovery in a distributed database environment involves ensuring that the entire transaction has completed successfully before issuing a COMMIT to each of the subcomponents in the overall transaction. This can often be a cumbersome chore, and the issue of the two-phase commit is addressed in detail later in this text. One popular alternative to the two-phase commit is replicating information and relying on asynchronous replication techniques to enforce the data integrity. Asynchronous replication refers to Oracle snapshots and requires a master-slave type of configuration, whereby a master database relays updates to the slave database on a periodic basis (using Oracle snapshots to create master-slave replication is discussed in more detail later in this chapter). The snapshot approach makes sense when an overall system does not require instant integrity.

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