Abstract: Performance-based caching may be implemented for query plan caches that are used to provide query plans to perform queries instead of generating query plans to perform queries. Performance metrics for queries performed at a database may be collected and used to cache query plans generated for the queries. When a query is received that matches one of the queries, the cached plan corresponding to the matching query may be used to perform the query.

Abstract: Multi-type attribute indexes may be implemented for document databases. When a request to perform a query at a document database is received that is directed toward in indexed attribute that has multiple data types for values stored in the multi-type attribute index, a predicate in the query may be replaced with a different predicate that is applicable to search the multi-type attribute index according to a sort order for the multiple data types stored in the at multi-type attribute index. A plan that includes the different predicate may be performed in order to provide a result of the query to a user.

Abstract: Processing responsibility for a data set may be split according to separately stored partitions of the data set. A data set may be stored in different storage units that separately store different partitions of the data set. Mapping information may be maintained indicating the assignment of a node to process access requests to multiple partitions of a data set. A split event may be detected for the node, and one or more partitions assigned to the node may be reassigned to a different node. The storage units for the reassigned partitions may be made accessible to the different node. Then mapping information can be updated to indicate change in assignment from the original node to the different node so that the different node can begin processing access requests for the reassigned partitions.