BACKGROUND

Background and Relevant Art

Frequently, database users need to make schema (e.g. change the type of a column) or data (e.g. split the Name column into two columns: First and Last name) modifications which require updating a large volume of data. This might be part of further application upgrades or due to some flaw in the original design of the schema. Such operations may require an update on every row in the table of a database. Currently, these operations can only be performed offline which introduces a huge amount of downtime for the application. While the modification is happening, the database tables remain inaccessible, which could lead to many hours of unavailability for some large tables.

Moreover, when these changes are part of application upgrades, there is usually multiple schema or data transformations that need to occur before the new application can be deployed. For example, Application V1 requires database schema V1 whereas Application V2 requires schema V2.

The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.

BRIEF SUMMARY

One embodiment illustrated herein includes a method that may be practiced in a computing environment. The method includes acts for transforming a database while allowing the data in the database to be available to database users during the transformation of the database. The method includes creating a new version of metadata for an old copy of database items for the database for transforming the old copy of database items to a new copy of database items for the database to transform items in the old copy of database items. The method further includes creating a copy of data items to be transformed in the old copy of database items while applying a transformation to the data items to be transformed in the old copy of database items while migrating data from the old copy of database items to the new copy of database items to transform data items in the old copy of database items. The method further includes while migrating data from the old copy of database items to the new copy of database items, servicing user queries made against the old copy of database items to allow the database to remain online while transforming data items in the database.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

