Amazon Technologies, Inc.

Anand Kumar Thakur

David Charles Wein

Gaurav Kumar Gupta

Alexandre Olegovich Verbitski

Upendra Govindagowda

Saleem Mohideen

Jin Chen

Murali Brahmadesam

Navaneetha Krishnan Thanka Nadar

Hong Yang

James C Nasby

Commit time logging is performed as part of implementing time-based Multi-Version Concurrency Control (MVCC). A query engine may determine a commit time for a database transaction is committed to a database by applying MVCC to select different versions of data in the database according to transaction commit times. The query engine may store the commit time for the database transaction in a log structure stored in a non-volatile data store. A segment describing the log structure maintained in a volatile memory maintained in a volatile memory may be updated to include the commit time for the database transaction.

Commit time logging for time-based multi-version concurrency control

Clock times may be stored at nodes of a database system that are used to provide access to database data using Multi-Version Concurrency Control (MVCC) and implement isolation for distributed transactions. When an access request is received at a processing node of a database, the snapshot time of the access request is determined. The snapshot may be a range of time, with an earliest and latest timestamp. If the snapshot time has a latest time stamp greater than a current timestamp in the clock time, then the clock time may be updated. The clock time and snapshot time may be used to implement time-based MVCC to select a version of a tuple stored in the database to use for performing the access request.

Increasing commit times at database shards for implementing consistency and isolation for distributed transactions

Distributed execution of transactions may be performed across shards of a scalable database table. Instructions to perform as part of a transaction with respect to one or more database tables may be received. The instructions may be evaluated with respect to metadata obtained for the database tables to determine an assignment distribution of computing resources of the database system to data that can satisfy the access request. The commit protocol for the transaction may be determined according to the assignment distribution of the computing resources. After a request to commit the transaction is received, the transaction may be committed according to the determined commit protocol.

Distributed transaction execution across shards of scalable database tables

Lease-based consistency may be implemented for databases to handle failovers. A database node may obtain a consistency lease that describes a point in time determined from a time-to-live amount added to a consistent point in time for database data. While the consistency lease is valid, Multi-version Concurrency Control (MVCC) snapshots assigned by the database node can be used to handle requests to access the database data. Once expired, the database node may have to renew the consistency lease in order to continue to handle write and read requests.

Lease-based consistency management for handling failover in a database

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Anand Kumar Thakur