Re: Transitive Closure with XDb1

> > Could you show RDM's transitive closure equivalent?
>
> Paul said: But we can extend our DBMS by explicity including a "TClose"
> operator that takes a (two-columned) relation as its argument and returns
> a relation that is the transitive closure. Then TClose(Contains) is:
>
> whole part
> ===== ====
> universe john
> universe mary
> universe mars
> universe venus
> mars john
> venus mary

Technically, the above output using TClose(Contains) is incorrect. The parts of universe should be mars, venus, john and mary. No output row represents a person or a planet. It instead lists relationships between universe and john, universe and mary, etc.

In addition, using the more appropriate schema T_Contains, T_Planet and T_Person, how does one use TClose()? XDb1's T_Relative() works for hierarchies consisting of different kinds of things (ie Planet, Country, State, City, House, Person, including those added at run-time). In addition, how does one use TClose() to get parts of mars, since mars is not a table but a row? XDb1's T_Relative() returns parts of mars. Received on Thu May 13 2004 - 02:59:35 CEST