8
Copyright © Oracle Corporation, 2002. All rights reserved.
Redo and Archiving
8-2
Copyright © Oracle Corporation, 2002. All rights reserved.
Objectives
After completing this lesson, you should be able to:
•
Explain how to measure redo resource contention
•
List the causes of redo contention
•
Detail the LGWR algorithm and tuning concepts
•
Identify redo-less operations and their likely effect
on performance
•
Describe the ARCH process and best archiving
practices
8-3
Copyright © Oracle Corporation, 2002. All rights reserved.
Redo Architecture Concepts
•
Physiological logging:
–
Page actions: Change Vectors
–
Minitransactions: Redo Records
•
Page fix rule
•
Write ahead log
•
Log force at commit
•
Logical ordering of redo
8-4
Copyright © Oracle Corporation, 2002. All rights reserved.
Logging Methods
TABLE A
INDEX C
INDEX B
8-5
Copyright © Oracle Corporation, 2002. All rights reserved.
Logging Methods
Logical Log
insert operation
delete operation
Physiological Log
dba A, delete op, insert op
dba B, delete op, insert op
dba C, delete op, insert op
Physical Log
C'
B
C
A
B'A'
After Images
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