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1. Error RecoveryAndLogging.Undo, Redo,Undo-redo
LoggingAnd RecoveryMethods.
PRESENTED BY:
BORIGI SHREEKA-
230101120153
KONISIKA TRILOK-
230101120154
SANJAYA KUMAR PANDA-
230101120155
RUDRA LENKA-230101120156
YAJNADATTA PATTANAYAK-
230101120157

2. Introduction to
Error Recovery
2
This is a process that takes action
against the error to get the
negative effects reductions as
much as possible, also known as
the ability of the compiler in which
it takes action and resumes
parsing after taking an action over
syntactical error if required. When
we are talking about Error
Recovery we must take about first
Error Detection.

3. Undo and Redo
Operations:
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UNDO:This involves reversing the changes
made by an incomplete transaction (one
that hasn't been committed) due to a crash.
The system uses the transaction log, which
keeps track of all database modifications, to
identify these uncommitted changes and
revert them.
REDO: This ensures that all committed
transactions (ones that successfully
completed) are reflected in the
database even after a crash. The log
helps identify these transactions, and
the system replays the changes they
made to bring the database to a
consistent state.

4. Undo-Redo Logging
 UNDO-REDO LOGGING IS A COMBINED
APPROACH THAT INCORPORATES BOTH
UNDO AND REDO LOGGING TECHNIQUES FOR
RECOVERY. IT PROVIDES A MORE ROBUST
RECOVERY MECHANISM BY ALLOWING FOR
BOTH ROLLBACK AND REDO OPERATIONS
DURING RECOVERY
 UNDO-REDO LOGGING ENSURES THAT
TRANSACTIONS CAN BE EFFICIENTLY ROLLED
BACK OR REDONE TO MAINTAIN DATA
CONSISTENCY AND RECOVER FROM
FAILURES EFFECTIVELY.

5. Recovery Methods
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 Walt Disney Crash Recovery: Crash
recovery is the process of restoring a
database to a consistent state after a
system crash or failure. It typically
involves replaying logged operations from
the log to redo or undo incomplete
transactions
 Media Recovery: Media recovery is the
process of restoring a database after a
disk failure or corruption. It involves
restoring data from backups or using log-
based recovery techniques to recover lost
or damaged data.

6. This is an optimization technique used alongside
redo-undo logging.
At specific points in time, the system takes a
checkpoint, which is a snapshot of the consistent
database state along with the log position up to
that point.
During recovery, the system can start from the
latest checkpoint, reducing the amount of log
required for redo/undo operations.
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7. ARIES Recovery Algorithm
 ARIES (Algorithm for Recovery and Isolation
Exploiting Semantics) is a widely used recovery
algorithm in DBMS. It provides efficient crash
recovery and supports concurrency control
mechanisms like locking and timestamp
ordering.

8. Here are some additional points to
consider:
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Idempotence: Both undo and redo operations
should be idempotent, meaning repeated
applications have the same effect as a single
application. This ensures data integrity during
recovery.
8) Durability: The transaction log entries must be
written to stable storage before the corresponding
database modifications occur. This guarantees that
the log reflects the actual state of the database.

9. Case Studies
Real-world examples of error recovery and
logging in popular DBMS platforms, such as
Oracle, MySQL, and PostgreSQL,
demonstrate the application of these
concepts in ensuring data integrity and
system reliability.
Future Trends
Emerging technologies and trends in error
recovery and logging in DBMS, such as
distributed logging and cloud-based recovery
solutions, are shaping the future of data
management and system resilience

10. Conclusion
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By employing error recovery and logging
techniques, DBMSs can maintain data integrity
and minimize the impact of system failures.

11. Thank you