10. Describe the different types of database requests and transactions. Database request is an SQL query where as a database transaction is combination of one or more SQL queries which executed successfully or aborted. In distributed database management system database requests and transactions are classified into two types. They are remote and distributed Remote request: Remote request is a database function that allows application and users to submit SQL statements that reference to a single remote database processing site Distributed request: Distributed request is a database function that allows users to submit SQL statements that reference to more than one database in a single statement. Remote Transaction: Remote transaction is a collection of several database requests which access data from a single remote database processing site. Distributed transactions: Distributed transaction is a collection of several database requests which allows referencing several different local or remote data processing sites. 11. Explain the need for the two- phase commit protocol. Then describe the two phases.
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