Amazon Technologies, Inc.

Microsoft Technology Licensing, LLC

Microsoft Corporation

Ramesh Shankar

Raman Mittal

Murali Brahmadesam

Daniel Edward Lovinger

Minsoo Oh

Ravisankar V Pudipeddi

Aaron William Ogus

Scott Colville

Huseyin Simitci

Sumit Kumar

Grant Alexander MacDonald McAlister

Seungmin Wei

Chien-Lung Yu

Patrick E Bozeman

Supriya Wickrematillake

Aadithya Chandramalle Gowda

Andrew Willis Callahan

Mukul Gupta

Kevin Liu

Crosbie Matthew Smith

Yi Wen Wong

Daniel E Lovinger

Ravisankar Pudipeddi

Interruptions in an ordered replication stream can be received from in a database. A database instance of the ordered replication stream may detect missing log records and then evaluate log records that are subsequently received to determine whether to update a portion of an in-memory data structure for performing database requests using a comparison of sequence numbers of the last update corresponding to the portion of the in-memory data structure indicated in the log record and the last update recorded for the portion of the in-memory data structure. For comparison indicating valid portions, the log record can be used and for comparison indicating invalid portions, the portion of the in-memory data structure can be made unavailable.

Recovering from interruptions in database replication streams

Connection loss may be minimized for performing database query engine changes. A distributed database system may include different instances of the query engine that provide access to a database. When an event to change the version of the query engine is detected, a copy of the database may be created and a new instance of the query engine created. Read-only access to the database may be maintained using the different instances of the query engine while the new instance may be upgraded to the different version of the query engine. Upon successful installation of the different version of the query engine at the new instance, the new instance may be given read-write access to the database using the copy of the database and other database instances may be upgraded to the different version of the query engine.

Minimizing connection loss when changing database query engine versions

Data loss thresholds are enforced when performing updates to mirrored data sets. When an update is received for a data set that is mirrored to other copies of the data set, an evaluation of the difference between the data set and the other copies of the data set may be performed. If the evaluation determines that the difference fails to satisfy a threshold for acceptable data loss at the other copies upon a failure of the data set, a data loss mitigation action may be applied to performance of the update until the difference satisfies the threshold.

Enforcing data loss thresholds for performing updates to mirrored data sets

Systems and methods are disclosed to implement a synchronous database mirroring technique using delayed visibility write operations. In embodiments, a durable log of write operations in a primary database is replicated to a secondary database. The two databases do not make corresponding operations durable in a synchronous manner. However, the two databases coordinate to provide a visible view of the two durable logs that is guaranteed be durable in both databases. In embodiments, the primary database may monitor the state of the durable log of the secondary database, and periodically update the visible range of the logs to include operations that have been made durable in both databases. Advantageously, the visible range of the logs is permitted to grow asynchronously from the logs themselves, so that the two databases can provide a synchronized visible view of the log data without placing timing constrains on the data's durability.

Synchronous database geo-mirroring using delayed visibility write operations

Adaptive replication of changes may be performed for copies of a database. Log records may be generated and stored that correspond to changes to a database while a database is being copied. If the changes to be applied to a copy of the database is less than or equal to a threshold number of changes, then the copy of the database may be updated using the stored log records. If the changes to be applied to the copy of the database are greater than the threshold number of changes, then the copy of the database may be updated using data stored in the database.

Adaptive database replication for database copies

A directory services implementation is provided to associate distributed file system (DFS) links with individual directory objects, and metadata to attributes thereof, to allow leveraging directory services features for DFS for a given namespace. For example, updating directory objects with modified metadata related to DFS links requires only that the directory object related to the link be updated rather than an entire directory object related to the corresponding namespace. Moreover, directory services functionalities such as querying can be utilized with DFS to provide efficient location of updated records. In this regard, efficient replication of DFS throughout a network is facilitated.

Efficient updates for distributed file systems

Systems, methods, and computer storage media for load balancing at a client device in a distributed computing environment based on a dynamic validity duration and utilization metrics of one or more data stores are provided. The client device selects a data store from a plurality of data stores that each maintains a copy of a datum. The selection of data stores by a client is based on utilization metrics of the data stores. The utilization metrics are stored at the client. A data store determines if a request for a particular datum may be fulfilled within a validity period associated with a request from the client. The validity period is dynamically changed by the client across multiple requests to aid in the load balancing process. Additionally, a gossip protocol may be used to propagate utilization metrics of a plurality of data stores across the system.

Load balancing in a distributed computing environment

A system and method for organizing and sorting targets received in a referral response and for realizing a target fail-back and a target priority policy in a distributed file system is provided. In one embodiment, a sorting method includes receiving a referral response in the form of a list of targets that are sorted into bounded sets. Having a sorted referral response in bounded sets provides a basis for implementing a target fail-back and a target priority policy. The computer system may select a target from a sorted list of targets sorted according to site-cost and/or target priority. Then, the computer system may determine if the set target is associated with a more preferred target when compared to all available targets in the sorted list and if not, switch back to a more preferred target.

System and method for determining target failback and target priority for a distributed file system

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Redmond, WA, United States of America

Ramesh Shankar