ONGOING MAINTENANCE AND GROWTH - Database Design and Development: An Essential Guide for IT Professionals - page 521

DATABASE

CRASH

3 p.m.

Rollforward

Log
File

DATABASE

Rollback

Users

DATABASE

Backup
File

11 p.m.

Up to last night

Restore and
reprocess

Figure 17-3 Database recovery methods.

TYPE OF FAILURE CORRUPTED RECOVERY METHOD RECOVERED

Transaction
Malfunction

Backward recovery

DATABASE DATABASE

Backward recovery OR
correct data OR restart from
checkpoint (Rectify cause of
bad data)

Bad
Data

DATABASE DATABASE

System
Crash

Backward recovery OR
restart from checkpoint

DATABASE DATABASE

Database
Damage

Forward recovery

DATABASE DATABASE

Figure 17-4 Database failures and recovery methods.

Initially, the DBA authorizes users with access privileges. The initial setup usually
enables the users to get started with the new database system. However, very soon,
changes to the access privileges are warranted. Here are some of the reasons for
revisions to access privileges: