Re: Any was to prevent a join if no columns are selected from a view?

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От Royce Ausburn
Тема Re: Any was to prevent a join if no columns are selected from a view?
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Msg-id A1D6E5EA-884F-4F46-8DFB-3EE4547333A4@inomial.com
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Ответ на Any was to prevent a join if no columns are selected from a view?  (Jason Long <mailing.lists@octgsoftware.com>)
Ответы Re: Any was to prevent a join if no columns are selected from a view?
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On 30/09/2011, at 8:57 AM, Jason Long wrote:

I thought I had read somewhere that Postges could ignore a join if it
was not necessary because there were no columns from the table or view
selected in the query.  Is this possible?

You might be thinking of this enhancement introduced in 9.0:


  • Remove unnecessary outer joins (Robert Haas)

    Outer joins where the inner side is unique and not referenced above the join are unnecessary and are therefore now removed. This will accelerate many automatically generated queries, such as those created by object-relational mappers (ORMs).

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