Zero downtime upgrade of database applications using triggers and calculated fields

摘要

An upgrade of a first version of a database application to a second version of a database application that both have a same data schema is initiated. The first database application has a first access schema such that at least one table in the data schema is linked to the first access schema. The second version of the database application has a second access schema such that at least one table in the data schema is linked to the second access schema. Subsequently, concurrent access is provided for each access schema to at least one database table in the data schema to the first and second versions of the database application. The concurrent access is enabled by a respective at least one table link object in each of the first access schema and the second access schema that is used by database views or stored procedures such access schema.

主权项

1. A method for implementation by one or more data processors forming part of at least one computing device, the method comprising:
initiating an upgrade of a first version of a database application to a second version of the database application that both have a same data schema, the first version of the database application having a first access schema comprising a first table link object linking to a database table in the data schema to the first access schema, the first table link object specifying a transient calculated field that is not persisted in the database table in the data schema, the transient calculated field being defined on the first table link object and not on the database table in the data schema such that changing of calculated field logic for the transient calculated field in the upgrade proceeds without requiring copying of the database table; and creating a second access schema for the second version of the database application, the second access schema comprising a second table link object linking the database table in the data schema to the second access schema, the first access schema differing from the second access schema, the first access schema and the second access schema providing concurrent access to the database table in the data schema to the first version of the database application via the first access schema and to the second version of the database application via the second access schema, the first table link object being consumable by one or more first database objects in the first access schema and acting as a first view to the database table in the data schema, and the second table link object being consumable by one or more second database objects in the second access schema and acting as a second view to the database table in the data schema.