| Dear all, I have a question concerning "an extension of Postresql/PostGIS with a spatio-temporal Abstract data type". PostgreSQL have many types categories : base types, composite types, domains, etc... I would like to extend PostGIS type system with a new abstract data type. This means that i must guaranty encapsulation of attributes : which means normally any user of a the DBMS may use the new type through it's operations and can not select over the types attributes (like geometry, line or point types) My question is : can this abstract data type be simply a compsite type (created whith CREATE TYPE and defined with plpgSQL) or must it be a base type (thus created inevitabely with a low level langage like C with typedef )? When i tried with a composite type, i could select over my type attributes! and it's not an abstract data type any more! And if it's defined with "typedef", must all operations be defined also in C or can some functions be defined with plpgsql? Thank you for you collaboration Donia |
