Database transaction schedule: Difference between revisions

Revision as of 21:43, 14 March 2024

Revision as of 21:48, 14 March 2024

Line 411:

In a '''recoverable schedule''', transactions only commit after all transactions whose changes they read have committed. A schedule becomes '''unrecoverable''' if a transaction <math>T_i</math> reads and relies on changes from another transaction <math>T_j</math>, and then <math>T_i</math> commits and <math>T_j</math> aborts.

{| class="wikitable"

! colspan="2" |F

!F: T1

! colspan="2" |F2

!F: T2

! colspan="2" |J

!F2: T1

|-

!F2: T2

!J: T1

!J: T2

!F: T1

!F: T2

!F2: T1

!F2: T2

|-

|R(A)

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The following examples are the same as the ones in the discussion on recoverable:

{| class="wikitable"

! colspan="2" |F

|+F & F2

! colspan="2" |F2

!F: T1

|-

!F: T2

!F2: T1

!F2: T2

!F: T1

!F: T2

|-

|R(A)