Secondary mappings to enable code changes without schema updates

摘要

Systems and methods are described for using secondary mappings in an Object Relational Mapping (ORM) system to enable source code changes to be implemented and carried out without requiring updates to the database schema. In order to use secondary mappings, one or more attributes of an object in the ORM system are annotated to indicate that they are secondary mapped attributes. The annotation can indicate to the ORM system that the various operations (e.g. read operations, write operations) referencing attributes of the object may need to be remapped if the column for the attribute being referenced does not actually exist in the database. For example, if no column is directly mapped to the attribute being referenced, the ORM system can remap the operation to point to a secondary data structure (e.g. a map stored in-memory) that will be used to store the value for that attribute.

主权项

1. A computer implemented method for using mapping information to decouple code modifications from database schema updates, said method comprising:
maintaining mappings between objects residing in an object relational mapping (ORM) system and tables residing in a database; annotating an attribute of an object in the ORM system with an annotation to generate an annotated attribute, the annotation indicating that the annotated attribute is capable of being stored as a secondary mapped attribute; receiving, by the ORM system, a read operation or write operation that references a specified attribute of the object; determining that the specified attribute referenced by the read operation or write operation corresponds to the annotated attribute of the object; determining that a first column exists in the database that is associated with the specified attribute of the object referenced by the read operation or the write operation; determining that a schema of the database has been updated to include the first column or if the first column does not exist, include a second column designated to store values for attributes that have been annotated with the annotation indicating secondary mapped attributes; mapping subsequent write operations to the first column in the database to generate a map in the ORM system; and removing the values in the second column.