Abstract: Methods, systems, and computer-readable media for versioned metadata management for a time-series database are disclosed. A metadata service of a distributed time-series database stores, to one or more metadata storage resources, first metadata descriptive of a table. The first metadata is associated with a version number in a logical sequence for the table. The metadata service stores, in a log, data indicative of one or more metadata updates for the table. The metadata update(s) are associated with an additional version number higher than the version number in the logical sequence. Responsive to a read request, the metadata service determines a most recent version number that has been applied from the log to the metadata storage resource(s). Responsive to the read request and based (at least in part) on the most recent version number, the metadata service returns either the first metadata or second metadata comprising the update(s).

Abstract: Replicated partitions of a database may be moved from one or more replica nodes to a different primary node. The replica nodes may maintain replicated partitions of one or more primary partitions of a primary node servicing access requests to the primary partitions. The replicated partitions may be copied to a different node in order to cause the processing of access requests directed to primary partitions to be serviced by the different node. Replicated partitions of a database may be moved from replica nodes to perform a split operation or a merger operation.

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.