Re: DELETE with LIMIT (or my first hack)

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От Bruce Momjian
Тема Re: DELETE with LIMIT (or my first hack)
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Msg-id 201012010157.oB11vuk07071@momjian.us
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Ответ на Re: DELETE with LIMIT (or my first hack)  (Daniel Loureiro <loureirorg@gmail.com>)
Ответы Re: DELETE with LIMIT (or my first hack)  (Daniel Loureiro <loureirorg@gmail.com>)
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Daniel Loureiro wrote:
> > 3. This doesn't work tremendously well for inheritance trees, where
> > ModifyTable acts as sort of an implicit Append node.  You can't just
> > funnel all the tuples through one Sort or Limit node because they aren't
> > all the same rowtype.  (Limit might perhaps not care, but Sort will.)
> > But you can't have a separate Sort/Limit for each table either, because
> > that would give the wrong behavior.  Another problem with funneling all
> > the rows through one Sort/Limit is that ModifyTable did need to know
> > which table each row came from, so it can apply the modify to the right
> > table.
> 
> So I guess that I have choose the wrong hack to start.
> 
> Just for curiosity, why the result of "WHERE" filter (in
> SELECT/DELETE/UPDATE) is not put in memory, i.e. an array of ctid, like an
> buffer and then executed by SELECT/DELETE/UPDATE at once ?

Informix dbaccess would prompt a user for confirmation if it saw a
DELETE with no WHERE.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +


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