Prevention, Detection and Repair of Database Corruption Part-2

Types of Corruption

Physical or structural corruption can be defined as damage to internal data structures which do not allow Oracle software to find user data within the database.

Logical corruption involves Oracle being able to find the data, but the data values are incorrect as far as the end user is concerned.

Physical corruption due to hardware or software can occur in two general places -- in memory (including various IO buffers and the Oracle buffer cache) or on disk. Operator error such as overwriting a file can also be defined as a physical corruption.

Logical corruption on the other hand is usually due to end-user error or non-robust(?) application design. A small physical corruption such as a single bit flip may be mistaken for a logical error. In general, for purposes of the paper we will categorize corruption under three general areas and give best practices for prevention, detection and repair for each:

· Memory corruption
· Media corruption
· Logical corruption


In Depth in the forthcoming comments....