OPTIMISTIC VERSIONING CONCURRENCY SCHEME FOR DATABASE STREAMS

摘要

Aspects of the subject matter described herein relate to versioning for databases. In aspects, two or more users may share the same version of data, such as a report, in a database. One of the users may seek to update the data. In response to a request from the user, a new version of the data is created. For data that is not updated via the request, the new version shares data with the previous version, thus saving space. For data this is updated, new segments within the database are created to store the updated data. Each user is allowed to access the data without blocking other users accessing the data.

主权项

1. A computer-executable storage device having computer-executable instructions, which when executed perform actions, comprising:
maintaining a first version of data of a database; allowing a first user and a second user to concurrently access the first version of the data; receiving a request from the second user to update the first version of data; while maintaining the first version of the data, creating a second version of the data by:
copying at least a part of a first portion that is affected by the update to create a second portion in a first data structure;changing data of the first or second portions to include data corresponding to the update;in response to changing data of one of the first or second portion, the first portion and the second portion having different versions of data; andupdating one or more other data structures to reference portions in the first version of the data that are also included in the second version of the data, wherein the first user accesses the first version of the data, and the second user accesses the second version of the data, the first version not affected by the update to the data.