Efficient Handling of Tuples with Embedded Large Objects
Stefan Dieker and Ralf Hartmut Güting
Praktische Informatik IV, FernUniversität Hagen
Modern database systems and storage manager toolkits usually provide
a large object abstraction. Very often large objects are not used as
standalone entities, but rather embedded within an aggregate of different
types, i.e. a tuple. Depending on the large object's size and access probability, query
performance depends on the representation of the large object: either inlined
within the aggregate or swapped out to a separate object. This paper describes
a sound and general large object interface extension which automatically
the representation of large objects according to their actual size. The
optimum threshold size for switching the large object's representation is
determined, based upon a linear cost model.
Furthermore, a SHORE-based implementation and its performance are presented.
It turns out that switching the representation of large objects yields
great performance improvements
for objects whose size is varying from quite small to large.
Keywords: Extensible database systems, data type
programming interface, large objects, tuple representation, Shore
Published: FernUniversität Hagen, Informatik-Report 236, August 1998