Collection Reference

Collection references are provided for reference and relationship members with dimension 0 (unlimited) or greater than 1.Collection references are also created for generic attribute members. Reference and and generic attribute members are always created al local references, i.e. the collection LOID will be created when inserting the first referenced instance to the collection, which also causes an instance update for the referencing object instance. For update relationship members, the collection LOID will be reserved and stored into the object instance when creating the instance.

There are two different kinds of collection references:

In case of multiple key collections the LOID in the collection property refers to key list database entry, where each entry contains the LOID to the database index entry and the internal key number created when defining a key for a complex data type (structure). In case of single key references, the collection property LOID directly refers to the index database entry.

ODABA supports different index types:

• Persistent and temporary indexes
• Transient indexes