Introduction to Transaction Processing: Serialization Graph and

School: University of Wollongong - Course: CSCI 235 - Subject: Accounting

CSCI235 Database Systems Introduction to Transaction Processing (3) Dr Janusz R. Getta School of Computing and Information Technology - University of Wollongong Introduction to Transaction Processing (3)file:///Users/jrg/235-2020-AUTUMN/LECTURES/WEEK05/12introductiontotransproc3/12introductiont... 1 of 1915/4/20, 10:33 pm

Introduction to Transaction Processing Outline Serialization graph Serialization graph testing protocol Two phase locking protocol (2PL) Timestamp ordering protocol TOPCreated by Janusz R. Getta,CSCI235 Database Systems,Autumn 20202/19 Introduction to Transaction Processing (3)file:///Users/jrg/235-2020-AUTUMN/LECTURES/WEEK05/12introductiontotransproc3/12introductiont... 2 of 1915/4/20, 10:33 pm

Serialization graph Serialization graphis constructed in the following way Sample construction of aserialization graph Create a nodeT1 Create a nodeT2and add an edge fromT1toT2 If a transactionT participates in a concurrent execution then we add a node labeled withT to aserialization graph If the transactionsTandTprocess conﬂicting operations such that T processes its operationfirst then we add an edge directed fromTto T --iji ij T1T2T3 Concurrent execution of database transactions write(x,10) write(x,20) TOPCreated by Janusz R. Getta,CSCI235 Database Systems,Autumn 20203/19 Introduction to Transaction Processing (3)file:///Users/jrg/235-2020-AUTUMN/LECTURES/WEEK05/12introductiontotransproc3/12introductiont... 3 of 1915/4/20, 10:33 pm

Serialization graph Create a nodeT3and add the edges fromT1toT3and fromT2toT3 Add an edge fromT2toT1 write(x,30) write(y,10) read(y) TOPCreated by Janusz R. Getta,CSCI235 Database Systems,Autumn 20204/19 Introduction to Transaction Processing (3)file:///Users/jrg/235-2020-AUTUMN/LECTURES/WEEK05/12introductiontotransproc3/12introductiont... 4 of 1915/4/20, 10:33 pm

Serialization graph A serialization graph fornonconﬂict serializableexecution of database transactions Create a nodeT1 Create a nodeT2 Add an edge fromT2toT1 Add an edge fromT1toT2 T1T2 Nonconflict serializable execution of database transactions read(x) read(x) write(x,x-10) write(x,x+20)