Re: [GENERAL] Re: Data warehousing

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От Chris Bitmead
Тема Re: [GENERAL] Re: Data warehousing
Дата
Msg-id 377771D4.C603FEB2@bigfoot.com
обсуждение исходный текст
Ответ на Re: Data warehousing  (Herouth Maoz <herouth@oumail.openu.ac.il>)
Ответы Re: [GENERAL] Re: Data warehousing
Re: [GENERAL] Re: Data warehousing
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Herouth Maoz wrote:

> Maybe I'm missing the point here, but it seems to me that if
> you simply use indices not as key definitions but as query
> accelerators (as in "index the living daylights out of"), then
> you may as well define a separate index on each and every
> field. Why do multiple-field indices in such a case?

Why do multi-field indexes? Umm. How about to avoid doing a sequential
scan? If your query depends on multiple fields then once you've found
the set based on the first index you would have to sequential scan that
subset based on the second condition, unless you have a multi-field
index.

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