Re: query progress indicator

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От Kris Jurka
Тема Re: query progress indicator
Дата
Msg-id Pine.BSO.4.56.0405120509100.5292@leary.csoft.net
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Ответ на query progress indicator  (David Garamond <lists@zara.6.isreserved.com>)
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On Mon, 9 Feb 2004, David Garamond wrote:

> [=============>           ] 56% ETA ...
>
> I know there is no such thing in Postgres right now (though there is
> pg_stat_activity). But is there database product that can do this?
>

When pg is processing a query it doesn't know how long it will take, so it
can't make an estimate.  Consider a query on a very large table with no
indexes such as "SELECT * FROM tab WHERE col = 1 LIMIT 1;"  As it will be
forced to do a sequential scan of the table there is no way of telling if
a matching row will be found on the first row or never which will take
wildly different amounts of time.

Kris Jurka


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