Hybrid database architecture for custom scale-out

A hybrid database storage system comprising:

• a first database;
• a second database;
• and
• a control layer that:
• receives a request to write a data record;
• assigns ownership of the data record to the first database;
• instructs the first database to store a primary copy of the data record;
• while the first database retains ownership of the data record, detects changes to the primary copy of the data record in the first database and propagates the changes to a shadow copy of the data record in the second database;
• transfers the ownership of the data record from the first database to the second database in response to determining one or more ownership transfer criteria are satisfied for the data record;
• and
• while the second database retains ownership of the data record, directs updates to the data record to the second database.

One or more tangible computer-readable storage media storing processor-executable instructions for executing a computer process, the computer process comprising:

• receiving a request to write a data record to a hybrid database storage system, the hybrid database storage system including a first database storing data according to a first database schema and a second database storing data according to a second database schema;
• assigning ownership of the data record to the first database in response to receiving the request;
• writing a primary copy of the data record to the first database;
• while the first database remains owner of the data record:
• detecting changes to the primary copy of the data record made in the first database, the changes including updated values to schema components of the first database schema;
• accessing a schema mapping to map the updated values to corresponding schema components defined with respect to the second database schema;
• and
• based on a schema mapping that schema components of the first database schema to corresponding components of the second database schema, constructing one or more queries executable to propagate the changes to a shadow copy of the data record stored in the second database;
• in response to determining a set of ownership transfer criteria are satisfied for the data record, transferring ownership of the data record from the first database to the second database;
• and
• subsequent to transferring the ownership, directing updates to the data record to the second database.