Consensus protocol for asynchronous database transaction replication with fast, automatic failover, zero data loss, strong consistency, full SQL support and horizontal scalability

One or more non-transitory storage media storing instructions which, when executed by one or more computing devices, cause:

• receiving, from a client at a leader server, a command to perform a change operation on a row of a table of a database, wherein:
• the row of the table is replicated on a replication group of servers such that each server within the replication group of servers stores a respective copy of the row of the table,
• the command is associated with a particular transaction,
• the replication group of servers includes the leader server and a plurality of follower servers, and
• the leader server is configured to perform data manipulation language (DML) operations on the row of the table and replicate the DML operations to the plurality of follower servers;
• performing, by the leader server, the change operation on the copy of the row of the table stored at the leader server;
• in response to the leader server performing the change operation, creating, by the leader server, a replication log record for the change operation in a replication pipeline to be replicated from the leader server to the plurality of follower servers asynchronously;
• in response to the leader server creating the replication log record for the change operation in the replication pipeline, returning a result of the change operation from the leader server to the client prior to receiving acknowledgment that the replication log record has been stored in replication logs of a consensus number of the plurality of follower servers;
• receiving, from the client at the leader server, a transaction directive command to perform a transaction directive operation for the particular transaction;
• and
• creating, by the leader server, a replication log record for the transaction directive operation in the replication pipeline to be replicated from the leader server to the plurality of follower servers based on a consensus protocol.