Microsoft Technology Licensing, LLC

Jeffrey A East

Steven John Lindell

Goetz Graefe

Jakub Kulesza

Alexandre Olegovich Verbitski

Ajay Kalhan

Tomas Talius

Sameet Harishanker Agarwal

Conor J Cunningham

Santeri Olavi Voutilainen

Yixue Zhu

Steven R Schmidt

Michael I Zwilling

Gregory A Smith

Clifford T Dibble

Albert L Lingelbach

Craig G Zastera

Luis Felipe

Andrei Marinescu

Embodiments are directed to providing distributed database service upgrades of database server instances in a computer cluster using multiple database server instances and to monitoring and maintaining a distributed database service during upgrade. In an embodiment, each computer system in a computer cluster instantiates at least two different database server instances on each of the nodes in the cluster. The first database server instances are configured to operate using a current distributed database version and the second instances are configured to operate using a new, updated distributed database service version. The computer system receives an indication that the distributed database service is to be upgraded. Then, based on the received indication, the computer system migrates database replicas from the first database server instances to the second database server instances which operate the new, updated service version, substantially without user-visible downtime.

Seamless upgrades in a distributed database system

A method of invalidating an unused log file in a database includes examining a discard log information storage area and determining if a discard log exists. If the discard log exists, the log is invalidated. The headers of each of the log files that have been fully invalidated are then invalidated. The discard log is then fully invalidated and a new log file may be generated on top of the discarded log. The method may be interrupted by a failure, a changeover, or crash and will be repeated until it completes.

Robust end-of-log processing

The resynchronization of multiple copies of a database after a divergence in transaction history in provided. In an illustrative implementation, algorithms are provided for synchronizing multiple copies of a database upon the occurrence of a divergence in transaction history. A data environment is provided having a database and a copy. The database environment operating in a manner where the database records some transactions and the copy recording some later transactions, but neither having an up-to-date set of data or log of data changes. In operation, the database and its copy compare transaction log sequence numbers to discern the changes database and/or database copy pages. During resynchronization, the database and/or its copy sends page specific information about changes that have not been performed on each other respectively. In this manner, the data environment may be resynchronized with minimal data transmitted and without a requiring a complete restoration of the database.

Resynchronization of multiple copies of a database after a divergence in transaction history

To avoid possible data corruption resulting from restoring data to a database from a backup set that is not valid for the database, attempted restore operations are intercepted before they are performed. The backup set is examined to determine whether it was created from the same recovery fork on which the database resides or an descendant of that recovery fork. The backup set is only allowed to be applied to the database if the backup set was created from one of these recovery forks. If not, the backup set is not allowed to be applied to the database.

Backup and restoration of data in an electronic database

A linked data structure verification system to verify the integrity of at least one linked data structure simultaneously by way of a verification setup phase and an integrity verification phase. Individual nodes are retrieved from a memory device and examined seriatim in optimal memory device location order. Nodes are retrieved and examined in optimal memory device location order for maximum memory device retrieval performance. Expected and/or actual node information about nodes in a given linked data structure are temporarily stored as records in an integrity verification table for only as much time as is necessary to verify any part of the node information prior to excising one or more unnecessary records from the integrity verification table.

Linked data structure integrity verification system which verifies actual node information with expected node information stored in a table

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Sammamish, WA, United States of America

Jeffrey A East