Distributed database systems including callback techniques for cache of same

A system comprising:

• a plurality of computing nodes, each configured to:
• host an instance of a distributed database service;
• store cached data of the distributed database service in a local memory;
• and
• provide a callback to other instances of the distributed database service responsive to updating the cached data;
• a storage pool accessible to the plurality of computing nodes, the storage pool configured to store data of a distributed database across the plurality of computing nodes, wherein the cached data comprises a portion of the data of the distributed database.

A method comprising:

• cache certain data of a distributed database in a cache in local memory of each of a plurality of computing nodes;
• service a request to update database data, by at least one of the plurality of computing nodes, by accessing the cache and modifying the cache;
• provide a callback, by the at least one of the plurality of computing nodes, to at least another of the plurality of computing nodes, responsive the request to update the database data;
• and
• update, by the at least another of the plurality of computing nodes, data in local memory of the another of the plurality of computing nodes responsive to the callback.