Abstract: Technologies are disclosed for improving the availability of a distributed application by computing scores for the application that indicate the extent to which the configuration of hosts implementing the application complies with best practices for maximizing availability. One score can be generated for the application based upon the physical location of the hosts used to implement the application and the components upon which the application is dependent. Another score can be generated for the application based upon the number of data centers that hosts executing the application are located in as compared to a minimum required number of data centers. Another score can be generated for the application based upon the distribution of hosts utilized to execute the application across data centers. Operations can be initiated for improving the scores, such as migrating a host to a new rack or server, or migrating a host to a different data center.

Abstract: Technologies are disclosed for merging and vending partial database schemas. A schema compiler exposes a network services application programming interface (API) for merging partial database schemas for a database. Prior to merging partial database schemas, the schema compiler can determine whether namespace conflicts exist between the partial database schemas. If no namespace conflicts exist between the partial database schemas, the schema compiler can merge the partial database schemas to create a merged database schema. The merged database schema can then be provided to a database service that provides the database. The API can also include methods for retrieving partial database schemas from the merged database schema, updating or replacing database schemas in the merged database schema, and deleting partial database schemas from the merged database schema.

Abstract: Disclosed are various implementations of systems that facilitate idempotence of transactions that are generated by a client application executed by a client device. Systems and methods described herein also facilitate cleanup of transaction data that is outside an idempotence window provided by an idempotence service.