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Message Posted: Sun, 18 Jun 2000 @ 10:35:52 GMT

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Subj:   Re: V2R3 Optimizer
From:   Robert Doss

Hi Eric,

  Also, is this a in-house built tool or standard publicly available product?  

The tool is OLAP Services from Microsoft - it is indeed checking on data types etc. - it may even be possible that this is the official Teradata translation of the ODBC call. Probably not - I'll check it out and suggest to MS that they use the ODBC call if it is not. However, it doesn't seem all that obtuse to me and I even seem to remember coding something like this myself years ago to do the same thing. In my opinion, the optmizer should pick these obvious cases out with some priority if for no other reason than to avoid doing work if a user sends a silly query.

  Finally, I still hesitate to push for any of the choices that you request. One exception is that I believe there is a system setting on how many lookaheads and how much energy the optimizer uses to find the best plan.  

Does anyone have any experience with this setting and have a handle on the benefits/tradeoffs etc? An on demand query and session level version of this is available in other products and is very useful. No software is perfect, and an optimiser cannot possibly get it right all the time. Tools to help when it does not can save an incredible amount of time. In my opinion, with more on-line use of data warehouse data they are almost essential. I know there is a back door for setting statistics - but because it is a back door it is unsafe to use. A few years ago, Mr Walter spoke about putting a safe interface in front of it. I am not aware of it being available.


Bob Doss

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