Re: The TransRelational Model: Performance Concerns

pc <magoo_at_pssstoff.org> writes:
> i wonder would we be seeing a different world now had the old core
> memory been as cheap and plentiful as today's.

there is actually a number of different issues ... the amount of core memory as well as the relatively performance.

i took some heat starting in the late '70s for claiming that the relative system performance had declined by a factor of ten over a 10-15 year period (disk performance had increased by 3-5 times but cpu & memory had increased by 50 times .,.. so the relative system disk performance declined by a factor of 10).

the disk division got annoyed and assigned their performance organization to refute the statements. they took a couple months and came back saying that i had slightly under stated the problem. this eventually turned into a user group presentation on recommendations about how to structure & use disks for better system performance. random recent posting somewhat related to the topic http://www.garlic.com/~lynn/2004q.html#76

I've frequently claimed that the CKD architecture from the 60s was a trade-off of i/o capacity vis-a-vis limited real memory ... aka it was possible to put the index structure on disk and have the i/o subsystem execute a program to find specific kinds of data and read only what was necessary into storage. this avoided having to use any of real storage for caching of either data and/or index pointers. by the mid-70s the resource constraint was starting to shift from real memory to i/o ... and CKD became the wrong trade-off in that environment. random past postings related to the CKD trade-off and the criteria that assumptions were based on totally reversing over a period of time http://www.garlic.com/~lynn/subtopic.html#dasd and slightly related posts on bdam &/or cics http://www.garlic.com/~lynn/subtopic.html#bdam

in the early 90s ... one of the large airline res systems were complaining that they had applications with (at least) ten impossible things that they couldn't do in the existing infrastructure. I looked at one of the applications (routes) that accounted for approx. 25percent of total system load and rewrote it from scratch.

Much of the fundamental architecture and assumptions hadn't changed since the 60s .... so I reset to zero and re-examined the fundamental architecture assumptions that had been made and tried to determine if they still applied (and if not, what could i do if I was starting totally from scratch). I got about a 100-fold speed up AND was able to implement all ten impossible features (which when done resulted in only a net 10-fold speed up .. since it was doing a lot more).

-- 
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/