Re: Calculated view fields (8.1 != 8.2)
От | Tom Lane |
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Тема | Re: Calculated view fields (8.1 != 8.2) |
Дата | |
Msg-id | 6320.1173203258@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Calculated view fields (8.1 != 8.2) (Gaetano Mendola <mendola@bigfoot.com>) |
Ответы |
Re: Calculated view fields (8.1 != 8.2)
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Список | pgsql-hackers |
Gaetano Mendola <mendola@bigfoot.com> writes: > [ 8.2 evaluates volatile functions in the targetlist of a view ] > If I mark the function as STABLE or IMMUTABLE then even with version > 8.2 the function is not evaluated. Is this the intended behavior? Yes; people complained that we needed to be more careful about the number of times volatile functions get evaluated. > I didn't see something about it in the release note. <listitem> <para> Do not flatten subqueries that contain <literal>volatile</> functions in their targetlists (Jaime Casanova) </para> <para> This prevents surprising behavior due to multiple evaluation of a <literal>volatile</> function(such as <function>random()</> or <function>nextval()</>). It might cause performance degradation inthe presence of functions that are unnecessarily marked as <literal>volatile</>. </para> </listitem> regards, tom lane
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