Time reservations for ensuring consistent reads in a distributed database without logging

Abstract

The subject matter described herein provides techniques to ensure that queries of a distributed database observe a consistent read of the database without locking or logging. In this regard, next-write timestamps uniquely identify a set of write transactions whose updates can be observed by reads. By publishing the next-write timestamps from within an extendable time lease and tracking a 'safe timestamp,' the database queries can be executed without logging read operations or blocking future write transactions, and clients issuing the queries at the 'safe timestamp' observe a consistent view of the database as it exists on or before that timestamp. Aspects of this disclosure also provide for extensions, done cheaply and without the need for logging, to the range of timestamps at which read transactions can be executed.