Object-relational based data access for nested relational and hierarchical databases

A computer program product comprising a computer readable storage medium having a computer readable program stored thereon, wherein the computer readable program, when executed on a computing device, causes the computing device to:

• obtain entity metadata constructs for an object relational mapping framework, the entity metadata constructs mapping fields in entities of an object model to fields in a data table of a nested relational database and identifying relationships between entities in the object model;
• obtain a nested relational data model of the nested relational database, the nested relational data model specifying tables and sub-tables of the nested relational database;
• map tables and sub-tables of the nested relational database to a plurality of separate entities of the object model, wherein at least one parent table is mapped to at least one top-level entity and at least one sub-table is mapped to at least one sub-entity of the at least one top-level entity;
• and
• access data in the nested relational database using the plurality of separate entities, wherein:
• the mapping is performed without normalizing the data of the tables and sub-tables of the nested relational database to a nested representation,
• mapping tables and sub-tables of the nested relational database to a plurality of separate entities of the object model comprises providing a nested relational entity provider and using the nested relational entity provider to perform the mapping,
• the nested relational entity provider loads a top level entity and at least one sub-entity of the top level entity using a single read operation on a record of the nested relational database, and
• the record includes at least one multi-value field identifying at least one sub-entity.

An apparatus, comprising:

• a processor;
• and
• a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to:
• obtain entity metadata constructs for an object relational mapping framework, the entity metadata constructs mapping fields in entities of an object model to fields in a data table of a nested relational database and identifying relationships between entities in the object model;
• obtain a nested relational data model of the nested relational database, the nested relational data model specifying tables and sub-tables of the nested relational database;
• map tables and sub-tables of the nested relational database to a plurality of separate entities of the object model, wherein at least one parent table is mapped to at least one top-level entity and at least one sub-table is mapped to at least one sub-entity of the at least one top-level entity;
• and
• access data in the nested relational database using the plurality of separate entities, wherein:
• the mapping is performed without normalizing the data of the tables and sub-tables of the nested relational database to a non-nested representation,
• mapping tables and sub-tables of the nested relational database to a plurality of separate entities of the object model comprises providing a nested relational entity provider and using the nested relational entity provider to perform the mapping,
• the nested relational entity provider loads a top level entity and at least one sub-entity of the top level entity using a single read operation on a record of the nested relational database, and
• the record includes at least one multi-value field identifying at least one sub-entity.

A method, in a data processing system, comprising:

• obtaining entity metadata constructs for an object relational mapping framework, the entity metadata constructs mapping fields in entities of an object model to fields in a data table of the nested structure database and identifying relationships between entities in the object model;
• obtaining a nested structure data model of the nested structure database, the nested structure data model specifying tables of the nested structure database;
• mapping tables of the nested structure database to a plurality of separate entities of the object model, wherein at least one first table is mapped to at least one top-level entity and at least one second table is mapped to at least one sub-entity of the at least one top-level entity;
• and
• accessing data in the nested structure database using the plurality of separate entities, wherein:
• the mapping is performed without normalizing the data of the tables of the nested structure database,
• mapping tables of the nested relational database to a plurality of separate entities of the object model comprises providing a nested relational entity provider and using the nested relational entity provider to perform the mapping,
• the nested relational entity provider loads a top level entity and at least one sub-entity of the top level entity using a single read operation on a record of the nested relational database, and
• the record includes at least one multi-value field identifying at least one sub-entity.