Microsoft Technology Licensing, LLC

Kangrong Yan

Balan Sethu Raman

Rajeev Bashyam Rajan

Xin He

Vladimir V Grebenik

Vladimir Kritchko

Michael James Zwilling

Sameet Harishanker Agarwal

Lewis S Bruck

Rajeev B Rajan

Techniques are disclosed for enabling the migration of data with minimized impact on consumers of the data. A data migration agent updates pointers to active data locations and coordinates a migration from a first data resource to a second data resource so that seamless migration may be carried out. A data access layer of a distributed computing environment can take advantage of the pointers and metadata written by the data migration agent to serve requests to resources of the distributed computing environment so that read availability is available regardless of migration status.

Seamless data migration across databases

Methods and computer-readable media for maintaining transactional link-level consistency between a database and a file system. A file system change is logged in a record of a database log and a file corresponding to the file system change is created in a file system folder. During a restart recovery process, an analysis operation and a conditional redo operation are performed based on the database log, and a conditional redo operation and an undo operation are performed based on the files in the file system folder. An undo operation is then performed based on the database log.

Maintenance of link level consistency between database and file system

In a database system that supports user-defined types, one or more fields of a user-defined type may be designated as containing data that is to be stored as a file outside of a database store, separate from the other fields of the type which are stored within the database. Instead of being stored within the database, the data in such a designated field of an instance of the user-defined type is stored as a file within the file system of a computer. Applications are provided 'out of band' access, via the file system of the computer, to the file in which the data of such a field is stored outside the database store. A component of the system intercepts file system open requests and checks security against the database store before allowing the open request to proceed. The component also notifies the database when file system close requests are received.

System and method for storing and retrieving a field of a user defined type outside of a database store in which the type is defined

A database view of a database is created which provides a transaction-consistent view of an existing database at a previous time. Each database view contains all the information needed to, along with the primary database, determine the contents of the primary database at a previous time. The database view consists of a side file corresponding to each data file in the primary database. The side files contain a copy of all data from the corresponding data file which has been changed since the database view was created. Sparse files may be used for the side files in order to conserve space. Page table data is kept in order to allow a quick determination as to whether the page from the primary database has been modified and the old version stored in the database view side file.

Transaction consistent copy-on-write database

A type of an object that can be persisted in a database store is defined by a user. The type definition comprises fields and behaviors, each field having a respective data type. One or more fields of the type definition may be designated as containing data of a type that is to be stored as a file outside of the database store and separately from the other fields of the type definition. When a request is received to store an object that is an instance of the user defined type, the data in any so designated field of the object is stored in a file outside of the database store, preferably within a file system of the computer on which the database store is implemented. The data in each of the other fields of the object is stored within the database store in the usual manner. The database store maintains a link, or reference, between the persisted object and the data of the field that is stored as a file outside of the database store. Applications are provided 'out of band' access, via the file system of the computer, to the file in which the data of given field is stored outside the database store.

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Issaquah, WA, United States of America

Kangrong Yan