Re: select count(*) is slow

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От aditya desai
Тема Re: select count(*) is slow
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Msg-id CAN0SRDHcVYtpadNDNEk7EHjX6re0UEunG-k1Vxi-ojPA5VK_1Q@mail.gmail.com
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Ответ на Re: select count(*) is slow  (Tom Lane <tgl@sss.pgh.pa.us>)
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Thanks Tom. Will try with numeric. Please ignore table and index naming.

On Tue, Apr 6, 2021 at 6:55 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
aditya desai <admad123@gmail.com> writes:
> Below query takes 12 seconds. We have an index on  postcode.

> select count(*) from table where postcode >= '00420' AND postcode <= '00500'

That query does not match this index:

> CREATE INDEX Table_i1
>     ON table  USING btree
>     ((postcode::numeric));

You could either change postcode to numeric, change all your queries
of this sort to include the cast explicitly, or make an index that
doesn't have a cast.

                        regards, tom lane

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