POSTGRES is an extended-relational database manager that supports inheritance, user-defined types, functions, and operators, ad-hoc queries, time travel, a rules system, tertiary storage devices, and very large typed objects, among other things. POSTGRES speaks postquel, a derivative of the quel query language originally designed at berkeley for the ingres database system. User functions may be written in C or in postquel. C functions will be dynamically loaded into the database server on demand, and either kind of function may be executed from the query language.
POSTGRES and the papers that describe it are available free of charge from toe.CS.Berkeley.EDU (188.8.131.52) in directory pub/postgres. The code is stored in a directory named after the latest release; at the time of this writing, that directory is postgres-v4r1. The list of officially-supported ports is short (decstations running ultrix 4.x and sparcstations). Unofficially, many more are supported -- people elsewhere have done the ports and distribute their versions of the code. The list of unofficial ports is available in pub/postgres as file UNOFFICIAL-PORT-LIST.
On Type Evolution: You ask explicitly about type evolution. We support schema modification on all classes, including user classes. This means that you can add attributes (instance slots) and methods at any time. Further, since postgres is a shared database system, such changes are instantly visible to any other user of the class.
The language syntax supports attribute deletion, but the system won't do it yet. Since all data is persistent, removing attributes from a class requires some work -- you need to either get rid of or ignore all the values you've already stored.
Contact: Paul Aoki <email@example.com>
The postgres code from uc berkeley is being commercialized by Miro Systems, Inc. [This seems to have been updated to Montage]
Contact: paula hawthorn (firstname.lastname@example.org) dave segleau (email@example.com)
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