System and method for transaction continuity across failures in a scale-out database

A method for resuming a transaction, comprising:

• using a first engine instance to coordinate execution of the transaction;
• wherein the transaction involves making updates at a plurality of participants;
• after all statements in the transaction have been executed, the first engine instance sending, directly or indirectly, prepare request messages to each participant of a plurality participants in the transaction;
• upon receiving prepare acknowledgement messages, directly or indirectly, from each participant of the plurality of participants, the first engine instance selecting a candidate commit time;
• initiating transmission of the candidate commit time to one or more backup coordinators;
• wherein the one or more backup coordinators include a second engine instance;
• in response to the first engine instance failing after selecting a candidate commit time and before the second engine instance has received the candidate commit time, establishing the second engine instance as a new transaction coordinator for the transaction;
• the second engine instance resuming the transaction by sending, directly or indirectly, prepare messages to each participant of the plurality of participants;
• upon receiving prepare acknowledgement messages, directly or indirectly from each participant of the plurality of participants, the second engine instance selecting a second candidate commit time;
• and
• the second engine instance changing status of the transaction to committed, and storing the second candidate commit time as commit time of the transaction.

A method comprising:

• establishing a lane between a client and a host, wherein the lane is a pipe through which the client may submit database statements to the host to cause the host to perform operations that target one or more rows in a database;
• determining that the lane is set to auto-commit;
• in response the lane being set to auto-commit, the host treating each statement received through the lane as a single-statement transaction;
• and
• after the host receives confirmation that the operations in a statement received through the lane have been successfully completed, the host automatically initiating a commit protocol without receiving any explicit commit command.

One or more non-transitory computer-readable media storing instructions which, when executed by one or more computing devices, causes:

• assigning rows of a table to a plurality of slices;
• wherein each row of the table is assigned to a single slice of the plurality of slices;
• for each slice of the plurality of slices, storing a plurality of duplicas;
• wherein each duplica of each slice contains rows of the table that belong to the slice;
• wherein, for each slice of the plurality of slices, storing the plurality of duplicas includes:
• storing a primary duplica in one persistent storage of a plurality of persistent storages;
• and
• storing one or more secondary duplicas in one or more persistent storages of the plurality of persistent storages;
• wherein each persistent storage of the plurality of persistent storages is local to and directly accessible only by a single engine instance of a plurality of engine instances;
• wherein each engine instance of the plurality of engine instances includes logic for accessing rows stored in the table;
• wherein the plurality of persistent storages includes a first persistent storage and a second persistent storage;
• wherein the first persistent storage stores the primary duplica for a particular slice that includes data for a particular row of the table;
• wherein the second persistent storage stores a particular secondary duplica for the particular slice;
• receiving a request to perform a transaction that affects data in the particular row of the table;
• initiating execution of the transaction at a first engine instance that is local to the first persistent storage;
• in response to the first engine instance ceasing to function prior to committing the transaction:
• establishing the particular secondary duplica on the second persistent storage as a new primary duplica for the particular slice;
• and
• causing the transaction to be resumed and committed by a second engine instance that is local to the second persistent storage.

A one or more non-transitory computer-readable media storing instructions for resuming a transaction, wherein the instructions include instructions which, when executed by one or more computing devices, cause:

• using a first engine instance to coordinate execution of the transaction;
• wherein the transaction involves making updates at a plurality of participants;
• after all statements in the transaction have been executed, the first engine instance sending, directly or indirectly, prepare request messages to each participant of a plurality participants in the transaction;
• upon receiving prepare acknowledgement messages, directly or indirectly, from each participant of the plurality of participants, the first engine instance selecting a candidate commit time;
• initiating transmission of the candidate commit time to one or more backup coordinators;
• wherein the one or more backup coordinators include a second engine instance;
• in response to the first engine instance failing after selecting a candidate commit time and before the second engine instance has received the candidate commit time, establishing the second engine instance as a new transaction coordinator for the transaction;
• the second engine instance resuming the transaction by sending, directly or indirectly, prepare messages to each participant of the plurality of participants;
• upon receiving prepare acknowledgement messages, directly or indirectly from each participant of the plurality of participants, the second engine instance selecting a second candidate commit time;
• and
• the second engine instance changing status of the transaction to committed, and storing the second candidate commit time as commit time of the transaction.