Database Replication Using Generalized Snapshot Isolation

Generalized snapshot isolation extends snapshot isolation as used in Oracle and other databases in a manner suitable for replicated databases. While (conventional) snapshot isolation requires that transactions observe the “latest” snapshot of the database, generalized snapshot isolation allows the use of “older” snapshots, facilitating a replicated implementation. We show that many of the desirable properties of snapshot isolation remain. In particular, read-only transactions never block or abort and they do not cause update transactions to block or abort. Moreover, under certain assumptions on the transaction workload the execution is serializable. An implementation of generalized snapshot isolation can choose which past snapshot it uses. An interesting choice for a replicated database is prefix-consistent snapshot isolation, in which the snapshot contains at least all the writes of locally committed transactions. We present two implementations of prefix-consistent snapshot...

• Type: Conference
• Year: 2005
• Where: SRDS
• Authors: Sameh Elnikety, Willy Zwaenepoel, Fernando Pedone
• Keywords: Prefix-consistent Snapshot Isolation, Replicated Database, Snapshot Isolation, SRDS 2005