Re: Index usage when bitwise operator is used

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От Kevin Grittner
Тема Re: Index usage when bitwise operator is used
Дата
Msg-id 46ED7CCD.EE98.0025.0@wicourts.gov
обсуждение исходный текст
Ответ на Index usage when bitwise operator is used  ("W.Alphonse HAROUNY" <wharouny@gmail.com>)
Ответы Re: Index usage when bitwise operator is used  (valgog <valgog@gmail.com>)
Список pgsql-performance
>>> On Thu, Sep 13, 2007 at  7:30 AM, in message
<f97d4e240709130530ve3cc522g61ccca23335618f4@mail.gmail.com>, "W.Alphonse
HAROUNY" <wharouny@gmail.com> wrote:

>    and each binary value of [variableCategory] may only hold a single binary
> '1'.

>  TBL1.CATEGORY & TBL2.CATEGORY <> 0  //-- where & is the AND bitwise
> operator

What about saying?:

  TBL1.CATEGORY = TBL2.CATEGORY

If your indexes include this and the other columns which cause the tables
to be related, one or both of them stand a pretty good chance of evaluating
to the lowest-cost method to join the tables.  Forcing a query to use an
index outside of it being the cheapest path is rarely productive.

-Kevin


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