Database Recovery Mechanism For Android Devices Pratik Patodi M. - - PowerPoint PPT Presentation

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Database Recovery Mechanism For Android Devices Pratik Patodi M. - - PowerPoint PPT Presentation

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References Database Recovery Mechanism For Android Devices Pratik Patodi M. Tech Project under the guidance of Prof. Deepak B. Phatak

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Database Recovery Mechanism For Android Devices

Pratik Patodi

  • M. Tech Project

under the guidance of

  • Prof. Deepak B. Phatak

Computer Science & Engineering Indian Institute of Technology, Bombay

Nov 3, 2012

Database Recovery Mechanism For Android Devices 1

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

1 Introduction

Android Motivation Problem Scope

2 Literature survey

Rollback Journal Write Ahead Logging

3 Shadow Paging

Overview Challenges

4 Adaptive Logging

Working

5 Conclusion and Future Work 6 References

Outline Database Recovery Mechanism For Android Devices 2

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References Outline Database Recovery Mechanism For Android Devices 3

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Introduction

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

“What is Android?”

  • An Open Source Operating System based upon the Linux kernel 2.6

provides[Bhu10]:

  • Comprehensive Library Set.
  • Multimedia User Interface.
  • Phone Application.

Introduction Database Recovery Mechanism For Android Devices 5

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

“What is Android?”

  • An Open Source Operating System based upon the Linux kernel 2.6

provides[Bhu10]:

  • Comprehensive Library Set.
  • Multimedia User Interface.
  • Phone Application.
  • It consists of 4 layers:
  • Linux Kernel.
  • Libraries and Android Runtime.
  • Application Framework.
  • Applications.

Introduction Database Recovery Mechanism For Android Devices 5

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Android Architecture

Figure: System Architecture [Arc]

Introduction Database Recovery Mechanism For Android Devices 6

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

“DataBase”

  • Need of DataBase:
  • Android- Open Source.
  • Applications require to store and update data.
  • Manage Data Efficiently - DataBase.

Introduction Database Recovery Mechanism For Android Devices 7

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

“DataBase”

  • Need of DataBase:
  • Android- Open Source.
  • Applications require to store and update data.
  • Manage Data Efficiently - DataBase.
  • Requirements of Database[Nor07]:
  • Embeddable in applications.
  • Small footprint.
  • In-Memory DBMS.
  • No code in the database.

Introduction Database Recovery Mechanism For Android Devices 7

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

  • SQLite
  • Native Android Database.
  • Executes SQL like commands.
  • Provides Rollback Journal and Write ahead logging.

(Update-in-place)

Introduction Database Recovery Mechanism For Android Devices 8

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

  • SQLite
  • Native Android Database.
  • Executes SQL like commands.
  • Provides Rollback Journal and Write ahead logging.

(Update-in-place)

  • Flash memory
  • Internal + External
  • Non-volatile, shock-resistant, and uses little power.
  • Rewrite = Erase + Write.
  • Fixed number of writes.

Introduction Database Recovery Mechanism For Android Devices 8

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Introduction

“Motivation”

Introduction Database Recovery Mechanism For Android Devices 9

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Problem Scope

Aim Replace update-in-place technique update-out-of-place for Android devices.

  • Update-in-place: Technique in which data is updated in the same

place where it is stored.

  • Update-out-of-place: Technique in which data is updated in the

copy of the original page. Technique Shadow paging

Introduction Database Recovery Mechanism For Android Devices 10

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Literature survey

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Rollback Journal

“Initial State”

Figure: Initial State [Ato]

Literature survey Database Recovery Mechanism For Android Devices 12

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Rollback Journal

“Acquiring A Read Lock”

Figure: Acquiring A Read Lock [Ato]

Literature survey Database Recovery Mechanism For Android Devices 13

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Rollback Journal

“Reading Information Out Of The Database”

Figure: Reading Information Out Of The Database [Ato]

Literature survey Database Recovery Mechanism For Android Devices 14

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Rollback Journal

“Obtaining A Reserved Lock”

Figure: Obtaining A Reserved Lock [Ato]

Literature survey Database Recovery Mechanism For Android Devices 15

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Rollback Journal

“Creating A Rollback Journal File”

Figure: Rollback Journal [Ato]

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Rollback Journal

“Changing Database Pages In User Space”

Figure: Changing Database Pages In User Space[Ato]

Literature survey Database Recovery Mechanism For Android Devices 17

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Rollback Journal

“Flushing The Rollback Journal File To Mass Storage”

Figure: Flushing The Rollback Journal File To Mass Storage[Ato]

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Rollback Journal

“Obtaining An Exclusive Lock”

Figure: Obtaining An Exclusive Lock [Ato]

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Rollback Journal

“Writing Changes To The Database File”

Figure: Writing Changes To The Database File [Ato]

Literature survey Database Recovery Mechanism For Android Devices 20

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Rollback Journal

“Flushing Changes To Mass Storage”

Figure: Flushing Changes To Mass Storage [Ato]

Literature survey Database Recovery Mechanism For Android Devices 21

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Rollback Journal

“Deleting The Rollback Journal”

Figure: Deleting The Rollback Journal [Ato]

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Rollback Journal

“Releasing The Lock”

Figure: Releasing The Lock [Ato]

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Rollback

“When Something Goes Wrong...”

Figure: When Something Goes Wrong... [Ato]

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Rollback

“Hot Rollback Journals”

Figure: Hot Rollback Journals [Ato]

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Rollback

“Obtaining An Exclusive Lock On The Database”

Figure: Obtaining An Exclusive Lock On The Database [Ato]

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Rollback

“Rolling Back Incomplete Changes”

Figure: Rolling Back Incomplete Changes [Ato]

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Rollback

“Deleting The Hot Journal”

Figure: Deleting The Hot Journal [Ato]

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Rollback

“Continue As If The Uncompleted Writes Had Never Happened”

Figure: Continue As If The Uncompleted Writes Had Never Happened [Ato]

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Write Ahead Logging

How Write Ahead Logging(WAL) works

  • WAL is opposite of Rollback Journal[WAL]
  • Original content are not modified.
  • Logs are written in separate WAL file.

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Write Ahead Logging

How Write Ahead Logging(WAL) works

  • WAL is opposite of Rollback Journal[WAL]
  • Original content are not modified.
  • Logs are written in separate WAL file.
  • Checkpoint
  • Size of WAL file >threshold
  • Original file is updated.

(update-in-place)

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Shadow Paging

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Shadow Paging

How Shadow Paging works

  • A copy of the original page is being created,shadow page.

Shadow Paging Database Recovery Mechanism For Android Devices 32

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Shadow Paging

How Shadow Paging works

  • A copy of the original page is being created,shadow page.
  • All updates in shadow page.

Shadow Paging Database Recovery Mechanism For Android Devices 32

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Shadow Paging

How Shadow Paging works

  • A copy of the original page is being created,shadow page.
  • All updates in shadow page.
  • Transaction is said to be COMMITTED, when the pointers are

modified.[Lor77]

Shadow Paging Database Recovery Mechanism For Android Devices 32

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Shadow Paging

How Shadow Paging works

  • A copy of the original page is being created,shadow page.
  • All updates in shadow page.
  • Transaction is said to be COMMITTED, when the pointers are

modified.[Lor77]

  • Failure before COMMIT-shadow page is ignored.

Shadow Paging Database Recovery Mechanism For Android Devices 32

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Shadow Paging

How Shadow Paging works

  • A copy of the original page is being created,shadow page.
  • All updates in shadow page.
  • Transaction is said to be COMMITTED, when the pointers are

modified.[Lor77]

  • Failure before COMMIT-shadow page is ignored.
  • Failure after COMMIT- database already consistent.

Shadow Paging Database Recovery Mechanism For Android Devices 32

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Shadow Paging

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Shadow Paging

Benefits of Shadow Paging

  • Overcome Flash Memory constraints.
  • Update-out-of-place.

Shadow Paging Database Recovery Mechanism For Android Devices 34

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Shadow Paging

Benefits of Shadow Paging

  • Overcome Flash Memory constraints.
  • Update-out-of-place.
  • Simple and Fast.
  • No log is needed.
  • No need to “read and then write”.

Shadow Paging Database Recovery Mechanism For Android Devices 34

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Challenges

Distorted file structure Solution: On flash memory, data location is not important than data access speed.[BCH05] Extra Space Required Solution: A free list can be maintained, Once transaction is committed the original page should be added in free list. storing log records is not required. Large Number of Small Updates Solution: Use Adaptive logging.

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Adaptive Logging

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Adaptive Logging

Overview

  • A-type update.

Adaptive Logging Database Recovery Mechanism For Android Devices 37

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Adaptive Logging

Overview

  • A-type update.
  • S-type update.

Adaptive Logging Database Recovery Mechanism For Android Devices 37

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Adaptive Logging

Overview

  • A-type update.
  • S-type update.
  • Default technique: Log-based.

Adaptive Logging Database Recovery Mechanism For Android Devices 37

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Adaptive Logging

Overview

  • A-type update.
  • S-type update.
  • Default technique: Log-based.
  • Log size >Threshold, Switch to Shadow paging.

Adaptive Logging Database Recovery Mechanism For Android Devices 37

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Adaptive Logging

Figure: Two Update Pattern [KJW10]

Adaptive Logging Database Recovery Mechanism For Android Devices 38

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Conclusion and Future Work

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Conclusion and Future Work

Conclusion

  • Android Operating System provides a native database engine,

SQLite.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 40

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Conclusion and Future Work

Conclusion

  • Android Operating System provides a native database engine,

SQLite.

  • SQLite uses rollback journal and write ahead logging.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 40

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Conclusion and Future Work

Conclusion

  • Android Operating System provides a native database engine,

SQLite.

  • SQLite uses rollback journal and write ahead logging.
  • Shadow paging is better for flash memory.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 40

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Outline Introduction Literature survey Shadow Paging Adaptive Logging Conclusion and Future Work References

Conclusion and Future Work

Conclusion

  • Android Operating System provides a native database engine,

SQLite.

  • SQLite uses rollback journal and write ahead logging.
  • Shadow paging is better for flash memory.
  • To further optimize use adaptive logging.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 40

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Conclusion and Future Work

Future Work

  • Short term goal

Implement shadow paging in SQLite.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 41

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Conclusion and Future Work

Future Work

  • Short term goal

Implement shadow paging in SQLite.

  • Long term goal

Implement adaptive logging.

Conclusion and Future Work Database Recovery Mechanism For Android Devices 41

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References I

Android Architecture. http://http://www.elinux.org/Android Architecture. [Online; accessed 3-Oct-2012]. Roolback Journal. http://www.sqlite.org/draft/atomiccommit.html. [Online; accessed 3-Oct-2012]. Siwoo Byun, Seongyun Cho, and Moonhaeng Huh. Flash memory shadow paging scheme for portable computers: Design and performance evaluation. ACM Trans. Database Syst., 39(3), October 2005. Vijay K. Madisetti Bhupinder S. Mongia. Reliable real-time applications on android os. http://www.ece.gatech.edu/~vkm/Android_Real_Time.pdf, 2010. Young-Seok Kim, Heegyu Jin, and Kyoung-Gu Woo. Adaptive logging for mobile device.

  • Proc. VLDB Endow., 3(1-2):1481–1492, September 2010.

Raymond A. Lorie. Physical integrity in a large segmented database. ACM Trans. Database Syst., 2(1):91–104, March 1977. Anil Nori. Mobile and embedded databases. In Proceedings of the 2007 ACM SIGMOD international conference on Management of data, SIGMOD ’07, pages 1175–1177, New York, NY, USA, 2007. ACM. References Database Recovery Mechanism For Android Devices 42

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References II

Write-Ahead Logging. http://www.sqlite.org/draft/wal.html. [Online; accessed 3-Oct-2012]. References Database Recovery Mechanism For Android Devices 43

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Architecture

Figure: Architecture [BCH05]

References Database Recovery Mechanism For Android Devices 44