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Data Consistency, Recovery, and Migration 4-43
Step 3: Roll Forward Log Records
Step 3: Roll Forward Log Records
The third step in fast recovery is to roll forward the logical log records that
were written after the most-recent checkpoint record. This action reproduces
all changes to the databases since the time of the last checkpoint, up to the
point where the uncontrolled shutdown occurred. Figure 4-6 illustrates this
step.
Figure 4-6
Fast recovery,
step 3
Fast Recovery: Step 3
OnLine rolls forward the logical log records written since the most-recent
checkpoint, reproducing the changes to the database since the checkpoint.
Records since the
checkpoint
Disk A
Logical log
Database changes since
the checkpoint rolled
forward