Abstract: A distributed database management system comprises database nodes located in a plurality of availability zones. The system receives a request to store a table, and determines to store a number of replicas of the table in one or more availability zones. The system obtains information indicating that one of the availability zones has been designated as preferred. The system identifies a set of database nodes in the preferred availability zone, where the number of database nodes in the subset is sufficient to determine quorum among the replicas. The replicas are stored on the identified set of database nodes.

Abstract: Localized lookups for performing access requests to a database may be implemented. Mapping information for storage nodes of a network-based service storing different data for different databases may be obtained by a routing application co-hosted with a client application of the database at a same container host. Access requests from the client application are handled by the routing application and sent to storage nodes identified using the mapping information. An authorization token may be included along with the requests to verify authorization to perform the access request at the storage nodes.

Abstract: A geographically distributed system using a hybrid, multi-master design is disclosed. The system may use global tables, for which both reads and writes may be performed locally, but with a single region serving as a master region. All strongly consistent reads and writes may be sent to the master region, whereas eventually consistent reads and writes may be performed in any region with a replica. The master region may not be statically assigned but may move from region to region. The master region may be assigned manually by client preference or may be assigned and updated automatically based on the time of day or workload characteristics.

Abstract: Systems and methods are provided to implement a database system configured to return the state of a data item upon failure of a condition check on the data item during a conditional write. In embodiments, a write request may specify an indicator to return the item state upon condition failure. The request may specify multiple database operations to execute as a transaction, where failure of a single condition check will cause the entire transaction to fail and an item state causing the failure to be returned. The returned state of the data item may include a selection of the item's attributes specified by the request. Advantageously, these features allow a client to easily obtain the precise cause of a write's failure. Moreover, because the item state is returned only when a conditional write fails and only when requested, the response size of most write requests remains unchanged.

Abstract: A geographically distributed system using a hybrid, multi-master design is disclosed. The system may use global tables, for which both reads and writes may be performed locally, but with a single region serving as a master region. All strongly consistent reads and writes may be sent to the master region, whereas eventually consistent reads and writes may be performed in any region with a replica. The master region may not be statically assigned but may move from region to region. The master region may be assigned manually by client preference or may be assigned and updated automatically based on the time of day or workload characteristics.