Mean absolute scaled error

From formulasearchengine
Revision as of 16:44, 9 January 2013 by 217.10.52.10 (talk)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Template:Orphan

In computer science the concept of a Lossless-Join Decomposition is central in removing redundancy safely from databases while preserving the original data.

Lossless-join Decomposition

Can also be called Nonadditive. If you decompose a relation R into relations R1 and R2 you will guarantee a Lossless-Join if R1R2 = R.

If R is split into R1 and R2, for the decomposition to be lossless then at least one of the two should hold true.

Projecting on R1 and R2, and joining back, results in the relation you started with.[1] Let R be a relation schema.

Let F be a set of functional dependencies on R.

Let R1 and R2 form a decomposition of R.

The decomposition is a lossless-join decomposition of R if at least one of the following functional dependencies are in F+ (where F+ stands for the closure for every attribute in F):[2]

Example

References

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.