Re: count * performance issue

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От Mark Kirkwood
Тема Re: count * performance issue
Дата
Msg-id 47D0AB2D.6080802@paradise.net.nz
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Ответ на Re: count * performance issue  (Craig James <craig_james@emolecules.com>)
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Craig James wrote:
>
> My question is: What do the other databases do that Postgres can't do,
> and why not?
>
> Count() on Oracle and MySQL is almost instantaneous, even for very
> large tables. So why can't Postgres do what they do?
>

I think Mysql can only do that for the myisam engine - innodb and
falcon  are similar to Postgres.

I don't believe Oracle optimizes bare count(*) on a table either - tho
it may be able to use a suitable index (if present) to get the answer
quicker.

regards

Mark

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