jack@odi.com (Jack Orenstein) (08/11/89)
Dennis Moore of RTI writes: In article 3386, dlw@odi.com (Dan Weinreb) writes: |Many CAD and CASE applications currently don't use any existing DBMS, |relational or otherwise. Or if they do, they only use it at a high |level of granularity, or for peripheral functions. Few or none of |them use a relational DBMS to store, say, individual transistors, or |whatever are the small elements in which the program primarily deals. |Since they're not using a relational DBMS now, there's no issue of |"staying with an evolving rdb". | |Dan Weinreb Object Design, Inc. dlw@odi.com This is common disinformation that OODB companies have been spreading in an attempt to generate a "need" for their product. Most CASE companies use RELATIONAL databases at the hearts of their products. For instance, ... Disinformation!? I work with Dan at Object Design, Inc., where we are building a C++-based OO DBMS. Dan wrote about "many" CAD and CASE companies, not "all". Furthermore, his information comes from *many* hours spent with CAD and CASE tool builders, discussing their requirements. Finally, before joining Object Design, Dan, myself, and many of our colleagues, spent several years at jobs where we had the opportunity to learn about the requirements of many "non-traditional" DBMS application areas, including CASE, MCAD, ECAD, geographic information systems, computer-aided publishing, and document management. Based on all this information, we concluded that there is a need for high performance for fine-grain manipulation of small, persistent objects. The OO DBMS companies are not generating a need, they are building products that respond to a need. We often hear comments of the form "we needed it yesterday". Dennis: Many databases have substantial object-oriented features; many of these databases are traditional RDBMSs. There is no exclusivity between OO- and R- DBMSs. For instance, ... [list of features] ... These features will improve our usability in several types of applications: data dictionaries (CASE/CAD/CAM/CAE/etc.), computer integrated manufacturing (CIM), expert systems, and others. Yes, and I can run ray-tracing software on an 8088-based PC, but I don't think that I'd have much luck selling the combination as a hot graphics box. The essential operation in many CAD applications, (the ones that Dan was referring to), is to locate an object given its id. This is a very fundamental operation, and performance will, to a large extent, depend on how it is implemented. Because the operation is so basic, it is not the sort of thing that can be changed once the DBMS has been built. It is therefore difficult for me to imagine how a relational DBMS can obtain the performance levels required by the customers being targetted by the OO DBMS builders. Jack Orenstein Object Design, Inc.