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.
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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