Distributed Transactions Each transaction coordinator is responsible for: Starting the execution of transactions that originate at the site. 。 Distributing subtransactions at appropriate sites for execution. Coordinating the termination of each transaction that originates at the site transaction must be committed at all sites or aborted at all sites. Each local transaction manager responsible for: Maintaining a log for recovery purposes Coordinating the execution and commit/abort of the transactions executing transaction at that site. coordinator TM transaction manager computer 1 computer n Database System Concepts-7th Edition 23.4 @Silberschatz,Korth and SudarshanDatabase System Concepts - 7 23.4 ©Silberschatz, Korth and Sudarshan th Edition Distributed Transactions ▪ Each transaction coordinator is responsible for: • Starting the execution of transactions that originate at the site. • Distributing subtransactions at appropriate sites for execution. • Coordinating the termination of each transaction that originates at the site ▪ transaction must be committed at all sites or aborted at all sites. ▪ Each local transaction manager responsible for: • Maintaining a log for recovery purposes • Coordinating the execution and commit/abort of the transactions executing at that site