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Re: Lucid statement of the MV vs RM position?

From: Pickie <keith.johnson_at_datacom.co.nz>
Date: 27 Apr 2006 14:48:44 -0700
Message-ID: <1146174524.598733.305370@i40g2000cwc.googlegroups.com>


Yes David, it was worth reading, thank you.

One of the problems when discussing the Pick-MV world is that there is thirty-some years of changes. The original idea is described in a 1965 paper by Don Nelson, while the version known as R83 is looked on as the archetype for "Pick". Universe now has SQL support, so maybe it is a full-fledged DBMS?

When Prime Information (Universe's progenitor)came up with the idea if having the system re-size the files continuously (called "dynamic" vs the standard "static" files), it didn't work for a while. Re-sizing was always a horrendous task in Pick machines as the files (tables) grew - at one site I was on it took over 24 hours to do "the big 'un". The latest Pick-alike (called QM) was written without any static files at all. Transactioning was added to the various Pick-alikes at different times. I'd use it ("like a shot" as I said at a job interview), but most of the applications I've seen have been around for a good while and don't use it.

Interestingly, Don Nelson conceived that there would be four 'engines'.  One for getting data out, one for putting data in, another for formatting reports, and the fourth for changing the data structure. As Dick Pick developed it, the formatting overtook the engine for getting data out - that is, the two were merged (at least, that's my view of the situation). The engine for putting data in was not built, instead that job was carried out by the application programmer using Ken Simm's version of BASIC.

The Pick/Nelson system did not have the idea of 'declarative' statements. You must remember that we are talking early '70's when most of the ideas were implemented. I might add that the original Pick "thing" was an extremely weird one. It was written using its own assembler. When they wanted to port to a new chip, they only had to re-write the small part that interpreted the assembler code. A really cool idea, but apparently the way it was coded was immensely interlinked and very tricky. Apparently the assembler code was largely a transcription of a set of diagrams Don Nelson did long before any hardware was available.

You might like to read Don Nelson's paper at http://www.tincat-group.com/mv/GIRLS.pdf Received on Thu Apr 27 2006 - 16:48:44 CDT

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