Notes10 - CS245:DatabaseSystem Principles Notes10:MoreTP...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
CS 245 Notes 10 1 CS 245: Database System  Principles Notes 10: More TP Steven Whang
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 2 Sections to Skim: Section 18.8 [18.8] Sections 19.2 19.4, 19.5, 19.6 [none, i.e., read all Ch 19] [In the Second Edition, skip all of Chapter 20, and  Sections 21.5, 21.6, 21.7, 22.2 through 22.7]
Background image of page 2
CS 245 Notes 10 3 Chapter 19 [19]   More on transaction      processing Topics: Cascading rollback, recoverable schedule Deadlocks Prevention Detection Long transactions (nested,  compensation)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 4 Example:          T   T W j (A)   r i (A)   Commit T i Abort T j ……  Non-Persistent Commit (Bad!)
Background image of page 4
CS 245 Notes 10 5 Example:          T   T W j (A)   r i (A)   Commit T i Abort T j ……  Non-Persistent Commit (Bad!) avoided by recoverable schedules
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 6 Example:          T   T W j (A)   r i (A)   w i (B) Abort T j                                                                [ Commit T i] ……  Cascading rollback (Bad!)
Background image of page 6
CS 245 Notes 10 7 Example:          T   T W j (A)   r i (A)   w i (B) Abort T j                                                                [ Commit T i] ……  Cascading rollback (Bad!) avoided by avoids-cascading- rollback (ACR) schedules
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 8 Schedule is conflict serializable T j          T i But not recoverable
Background image of page 8
CS 245 Notes 10 9 Need to make “final’ decision for each  transaction: commit decision  - system guarantees  transaction will or has completed, no  matter what abort decision  - system guarantees  transaction will or has been rolled back     (has no effect)
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 10 To model this, two new actions: C i  - transaction T commits A i  - transaction T i  aborts
Background image of page 10
CS 245 Notes 10 11 ... Back to example:                  T j T i      W j (A) r i (A) C i      can we   commit  here?
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 12 Definition T i   reads from T in S (T j   S   T i )  if (1) w j (A)   < S   r i (A) (2)  a j   < S    r i (A)        (< :  does not precede ) (3) If w j (A)   < S   w k (A)    < S    r i (A)  then        a k  < S  r i (A) 
Background image of page 12
CS 245 Notes 10 13 Definition Schedule S is recoverable  if  whenever T j    S  T   and  j   i and C  S then C j   < S   C i
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CS 245 Notes 10 14 Note: in transactions, reads and writes 
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

This document was uploaded on 03/08/2011.

Page1 / 62

Notes10 - CS245:DatabaseSystem Principles Notes10:MoreTP...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online