Re: why does this select hang postgres???

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От Fran Fabrizio
Тема Re: why does this select hang postgres???
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Msg-id 3B742691.42413DDD@mmrd.com
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Ответ на why does this select hang postgres???  (Jeremy Hansen <jeremy@xxedgexx.com>)
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Jeremy Hansen wrote:

> select * from env_info,summary,plat_info;
>
> Is my statement broken?  Is this not legal?  Postgres just sits there....

Is it just sitting there or are you making Pg work really hard?  You realize
that you are forcing a product combination of those three tables...if
there's 100 rows in each table, your result set is going to include
100*100*100 or 1,000,000 rows.  So if those tables are of even slightly
significant size, your result set is going to be ridiculous.

I'm guessing select * from three tables is not what you wanted, anyhow, but
without specifics....

-Fran


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