Object-Relational Mapping Based On Virtual Columns

摘要

A server system allows object relational mapping. Objects of an object type are stored as records in a table corresponding to the object type. The server system allows new attributes to be added to an object type without altering the corresponding table. The object type comprises a set of mapped attributes that correspond to distinct columns of the associated table. The object type further comprises unmapped attributes that fail to map to distinct columns of the table. The table is associated with a virtual column for storing the unmapped attributes. The unmapped attributes of an object of the object type are encoded into a value and stored in the virtual column. The virtual column may be a column of the same table or a column of an auxiliary table. The unmapped attributes may also be stored as name value pairs in an auxiliary table associated with the table.

主权项

1. A method for mapping operations in an object model to operations in a relational model, the method comprising:
storing a representation of an object model comprising one or more object types, each object type associated with a table of a database, wherein objects of each object type map to records stored in the table; identifying an object type in the object model, the object type associated with a table comprising a set of columns, the table associated with a virtual column, the object type comprising:
a set of mapped attributes, wherein a mapped attribute is mapped to a distinct column of the table; anda set of unmapped attributes, wherein an unmapped attribute fails to map to a distinct column of the table; and storing an object of the object type, the storing comprising:
storing a record of the table corresponding to the object, wherein each mapped attribute of the object is stored in the record as a value of a column associated with the mapped attribute;representing the set of unmapped attributes of the object as an encoded value; andstoring the encoded value in the virtual column.