Conditional master election in distributed databases

A method, comprising:

• storing a plurality of replicas of a data at respective storage nodes of a distributed database, wherein the plurality of replicas forms a replica group that includes an elected master replica that waits for write acknowledgements from one or more non-master replicas before indicating write completion, and wherein the write acknowledgements from the one or more non-master replicas are received at the elected master replica before indicating write completion;
• receiving, at a first non-master replica of the one or more non-master replicas, a request to read the data, wherein the request does not require coordinating with the master replica, wherein the request specifies a type of read request out of a plurality of types of read requests supported by the distributed database, wherein the specified type of read request does not require further data of a write request that completed before the request to perform the request at the first non-master replica;
• and
• responding, by the first non-master replica to the request to read the data, comprising executing the read without coordinating with the master replica.

One or more non-transitory computer-readable storage media storing program instructions that, when executed on or across one or more computing devices, cause the one or more computing devices to implement:

• storing a plurality of replicas of a data at respective storage nodes of a distributed database, wherein the plurality of replicas forms a replica group that includes an elected master replica that waits for write acknowledgements from one or more non-master replicas before indicating write completion, and wherein the write acknowledgements from the one or more non-master replicas are received at the elected master replica before indicating write completion;
• receiving, at a first non-master replica of the one or more non-master replicas, a request to read the data, wherein the request does not require coordinating with the master replica, wherein the request specifies a type of read request out of a plurality of types of read requests supported by the distributed database, wherein the specified type of read request does not require further data of a write request that completed before the request to perform the request at the first non-master replica;
• and
• responding, by the first non-master replica to the request to read the data, comprising executing the read without coordinating with the master replica.