| From: | Kris Jurka <books(at)ejurka(dot)com> |
|---|---|
| To: | David Garamond <lists(at)zara(dot)6(dot)isreserved(dot)com> |
| Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: query progress indicator |
| Date: | 2004-05-12 10:13:45 |
| Message-ID: | Pine.BSO.4.56.0405120509100.5292@leary.csoft.net |
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| Thread: | |
| Lists: | pgsql-general |
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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