Mike W. Blasgen

Learn More
System R is a database management system which provides a high level relational data interface. The systems provides a high level of data independence by isolating the end user as much as possible from underlying storage structures. The system permits definition of a variety of relational views on common underlying data. Data control features are provided,(More)
The recovery subsystem of an experimental data management system is described and evaluated. The transactmn concept allows application programs to commit, abort, or partially undo their effects. The DO-UNDO-REDO protocol allows new recoverable types and operations to be added to the recovery system Apphcation programs can record data m the transaction log(More)
Sequences of character strings with an order relation imposed between sequences are considered. An encoding scheme is described which produces a single, order-preserving string from a sequence of strings. The original sequence can be recovered from the encoded string, and one sequence of strings precedes another if and only if the encoding of the first(More)
If other processes request the lock while it is granted then they are placed in a queue of waiters and suspended. When the lock becomes available, requests are granted in first-come first-served order. Setting and clearing a lock costs ten instuctions if no waiting is involved. If waiting is involved,it costs 50 instructions plus two process dispatches(More)
0018-8670/99/$5.00 © 1999 IBM IBM SYSTEMS JOURNAL, VOL38, NOS 2&3, 1999 BLASGEN ETAL. System R is an experimental data base management system that was designed to be unusually easy to use. System R supports a high-level relational user language called SQL, which may be used by ad hoc users at terminals or by programmers as an imbedded data sublanguage in(More)
Generally it is easier to express complex ideas symbolically by sketching them on paper rather than by using other means of communication. When such two-dimensional representations were applied to computer output, they resulted in the development of computer graphics.' But they are only now being applied to the input. We anticipate an evolution in input(More)
The System R project started under the direction of Frank King at IBM Research probably around 1972. By then Ted Codd’s pioneering paper was 18 months old, and it was obvious to a lot of people that one should build a prototype to test out his ideas. Unfortunately, Ted was not a permitted to lead this effort, and he went off to consider natural language(More)
  • 1