High availability with consensus in database systems

A database management system comprising:

• a first set of nodes for maintaining system configuration data;
• a second set of nodes for storing user data, the second nodes being separate from the first set of nodes;
• at least one processor;
• and
• at least one memory, the memory including computer-executable instructions that, when executed by the at least one processor, cause the processor to:
• configure the first set of nodes of the database management system to:
• determine an instantaneous state of the database management system;
• in response to determining the instantaneous state, generate system configuration data using a consensus-based replication protocol to maintain the system configuration data in the first set of nodes by:
• writing an indication of a target configuration of the second set of nodes to system configuration data;
• and
• replicating the system configuration data amongst the first set of nodes using the consensus-based replication protocol;
• and
• provide the system configuration data to the second set of nodes of the database management system;
• and
• configure the second set of nodes to:
• store local configuration data representing the configuration of the second set of nodes;
• receive the system configuration data from the first set of nodes;
• and
• implement a state machine that is arranged to modify a configuration of the second set of nodes according to the system configuration data by:
• processing the system configuration data using the state machine to identify one or more differences between the local configuration data and the system configuration data;
• and
• modifying the local configuration data according to the one or more differences,
• wherein the second set of nodes are arranged to replicate user data according to a non-consensus-based replication protocol by which a first node of the second set of nodes can commit a transaction on user data prior to replicating the committed transaction to a second node of the second set of nodes.

A non-transitory computer-readable storage medium comprising computer-executable instructions that, when executed by at least one processor, cause the at least one processor to:

• configure a first set of nodes for maintaining system configuration data of the database management system to:
• determine an instantaneous state of the database management system;
• in response to determining the instantaneous state, generate system configuration data using a consensus-based replication protocol to maintain the system configuration data in the first set of nodes by:
• writing an indication of a target configuration of a second set of nodes to system configuration data, the second set of nodes storing user data and being separate from the first set of nodes;
• and
• replicating the system configuration data amongst the first set of nodes using the consensus-based replication protocol;
• and
• provide the system configuration data to the second set of nodes of the database management system;
• and
• configure the second set of nodes to:
• store local configuration data representing the configuration of the second set of nodes;
• receive the system configuration data from the first set of nodes;
• and
• implement a state machine that is arranged to modify a configuration of the second set of nodes according to the system configuration data by:
• processing the system configuration data using the state machine to identify one or more differences between the local configuration data and the system configuration data;
• and
• modifying the local configuration data according to the one or more differences,
• wherein the second set of nodes are arranged to replicate user data according to a non-consensus-based replication protocol by which a first node of the second set of nodes can commit a transaction on user data prior to replicating the committed transaction to a second node of the second set of nodes.