Single-operation on-line schema evolution

摘要

A method for modifying an original data object in a database using a single command is disclosed. The single command is first validated. Once the command has been validated a ghost data object is created using the new definition. The ghost data object is populated with data from the original object. The transaction log records from the original data object are applied to the ghost data object. The original data object is then locked for exclusive access. The final transaction log records from the original data object are applied to the ghost data object. In the final step the database switches to the new data object. Dependent objects are automatically transformed as part of the same operation.

主权项

1. In a computing system having a memory storing an original data object, a method for changing the original data object into a new data object using a single command, the steps of the method comprising:
validating the single command; creating a ghost data object based on a new data object schema definition indicated by the single command; populating the ghost data object with data from the original data object; applying transaction log records from the original data object to the ghost data object; exclusively locking the original data object; applying final transaction log records from the original data object to the ghost data object; and switching the ghost data object to become the new data object.