In computer science the concept of a Lossless-Join Decomposition is central in removing redundancy safely from databases while preserving the original data.
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Lossless-join Decomposition
Can also be called Nonadditive. If you decompose a relation
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. Let
Let
Let
The decomposition is a lossless-join decomposition of R if at least one of the following functional dependencies are in