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Message Posted: Fri, 02 Feb 2007 @ 21:23:51 GMT

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Subj:   Re: How Do You Measure/Validate Compression Savings?
From:   Victor Sokovin

  There was a Partner's user presentation on this topic a few years back (R5.x timeframe) which quantified different scenarios. But in my observations (unless the workload is PI, singleton, row inserts-retrievals) a set process that gets the benefit of 30% compression resulting in 30% fewer IOs for that object, always benefits from reduced CPU consumption.  

James, I don't like generic arguments and broad analogies but the timeframe you mentioned does remind me of some cases here in Europe. There used to be technically incompetent people at that time traveling from stand to stand at all possible "events", sometimes under the NCR flag, who would swear on savings on memory, CPU, storage and what not. And then there were people who tried to implement the newest features, got into all kinds of problems and risked their projects and professional carriers.

No analogies but, you know, you just learn from such experiences and become somewhat careful with your recommendations.

  > The idea of having a tool for MVC never occurred to me before I read the thread, probably because of the fear of compressing "small" tables and causing weird adverse effects elsewhere."  

  Haven't come across that scenario  

Why not? Even if the columns get loaded compressed into the spool you can still do all kinds of operations on them (take simple concatenation, for example) and then you can compare thus built "derived" columns with, say, some other compressed columns. In order to compare things like that some uncompression seems to be very likely, and I don't see how uncompression does not affect CPU usage.

But let's assume for a moment that MVC is like a free lunch with no side effects. Why such a useful tool does not just come with the database itself then? Why do you have to go to somebody else to buy the tool which seems to be such a must? It's like you buy a car and after you sign the check the dealer tells you that you'll be paying 30% more for your gas unless you go to the company XYZ and buy their tool.

I promise to go through the thread again and read up on MVC in general. The thread certainly makes you curious again about the things you thought you knew, which is always a good thing, but at the moment I can't help thinking: "What a strange thread this is!"



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