Re: Why Index is not working on date columns.

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От Kishore B
Тема Re: Why Index is not working on date columns.
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Msg-id 42567e060510250804y3329c901l21770d887dfcde42@mail.gmail.com
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Ответ на Re: Why Index is not working on date columns.  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Why Index is not working on date columns.  (Tom Lane <tgl@sss.pgh.pa.us>)
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Hi Tom,
 
Thank you for your response.
 
I surmise that you are testing on toy tables and extrapolating to what
will happen on larger tables. 
These tables participating here contain more than 8 million records as of now, and on every day, 200K records, will add to them.
 
 
Thank you,
Kishore.

 


 
On 10/25/05, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Kishore B <kishorebh@gmail.com> writes:
>  Can you guys please take a look at the following query and let me know why
> the index is not considered in the plan?

"Considered" and "used" are two different things.

The two examples you give have the same estimated cost (within two
decimal places) so the planner sees no particular reason to choose one
over the other.

I surmise that you are testing on toy tables and extrapolating to what
will happen on larger tables.  This is an unjustified assumption.
Create a realistic test data set, ANALYZE it, and then see if the
planner chooses indexes you like.

                       regards, tom lane

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