Database transaction schedule: Difference between revisions

Revision as of 21:29, 14 March 2024

Revision as of 21:37, 14 March 2024

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===Serializable===<!-- This section is linked from [[Concurrency control]] -->

A schedule is '''serializable''' if it is equivalent (in its outcome) to a serial schedule.

In schedule E, the order in which the actions of the transactions are executed is not the same as in D, but in the end, E gives the same result as D.

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Additionally, two view-equivalent schedules must involve the same set of transactions such that each transaction has the same actions in the same order.

In the example below, the schedules S1 and S2 are view-equivalent, but theyneither areS1 notnor S2 are view-equivalent to S3.

{| class="wikitable"

!S1: T1

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|-

|R(B)⁽¹⁾

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|Com.

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|R(B)⁽¹⁾

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|-

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|R(B)⁽²⁾

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|R(B)⁽²⁾

|W(B)⁽³⁾

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|-

|

|W(B)⁽³⁾

|

|W(B)⁽³⁾

|Com.

|