MANIPULATION OPERATIONS FOR AN INTERVAL EXTENDED RELATIONAL MODEL

We identify semantic problems associated with the querying and updatin g of spatio-temporal interval data and propose operations which allevi ate these problems. We first motivate two key requirements for the man ipulation of such data, namely that no two tuples of a relation should intersect or be mergeable. We then examine the properties of two oper ations, unfold and fold, and show how they can be used to define three further operations which, respectively: eliminate intersecting or mer geable data from a relation incorporating interval attributes, yieldin g a so-called canonical relation; add data to a canonical relation whi le preserving the canonicity property; and remove data from a canonica l relation while also preserving canonicity. We formally show the corr ectness of all these operations. An examination of their space and tim e requirements then leads us to define an equivalent set of optimised operations. We formally show the equivalence of the non-optimised and optimised operations, and discuss the performance gains of the latter.