DBKEY Datatype

This is an offshoot of the topic where you are exploring the comparison of graph databases with systems of relations. It's so tangential that I chose to start a new thread, rather than hijack your thread.

When DEC built Rdb, in the early 1980s, they included a datatype called DBKEY. The contents of a DBKEY, in some address space, was really the address of another record. Yeah, "record".

Their nomenclature at the time was to talk about "relations", "records",
"fields", and "global fields". A few years later, they were talking about
"tables", "rows", "columns" and "domains", after they adopted SQL. But the
SW engineering was really the same idea.

In any event, the availability of DBKEY as a datatype meant that a DB designer could, if he (meaning he or she) wanted to, extend the relational model by implementing his own arbitrary graph scheme. The documentation warned people against using this facility, but there it was... enough rope to hang yourself.

The consequences of "pinning" rows of a table in the DB address space were, of course, devastating. But the people who went down that road generally had to learn it for themselves.

BTW, the SW engineering that went into Rdb, and earlier into VAX DBMS (a CODASYL style database) was truly superb. Some of the cleanest implementation ever. DEC Rdb still survives as "Oracle Rdb". Received on Mon Jul 25 2005 - 16:08:22 CEST