extensible DBMS with ADT of spatial type is really spatial DBMS ?

   I want to implement a prototype of spatial DBMS . However ,i found ,a lot of

DBMS supporting spatial data type is implemented by this way : define an

abstract data type(ADT) of spatial type on the base of extensible DBMS. But i

don't think this is a real spatial DBMS , because the defination of ADT is

defined by user ,not implemented by DBMS itself, While a real spatial DBMS is

implemented by DBMS itself. That's ,for the so called sptial DBMS based on

extensible DBMS ,the spatial type is implemented in the level of application;

while for the real spatial DBMS ,spatial type is implemented in the level of

system!

    Dear readers, I am a new hand in this realm. Is what i said correct?

Would you please give me your opinion. Of course ,any other opinion about

the implemention of spatial DBMS is welcome!

    thank you!! Received on Thu Nov 01 2001 - 06:30:56 CET