High Availability and Scalability Support for Web Applications

A database query caching technique, GlobeCBC, can be used to improve the scalability of Web applications. This paper addresses the availability issues in GlobeCBC. Even though high availability is achieved by adding more resources, proper algorithms must be designed to ensure that the clients receive consistent responses amidst failures of the edge and origin servers. We present lightweight algorithms to detect and correct server failures while providing read-your-writes consistency. They exploit the fact that the query workload of Web applications is based on a fixed set of read and write templates. We show that these algorithms incur very low overhead using several microbenchmarks and a complete Web application benchmark