From: | Daniel Loureiro <loureirorg(at)gmail(dot)com> |
---|---|
To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
Cc: | Csaba Nagy <ncslists(at)googlemail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: DELETE with LIMIT (or my first hack) |
Date: | 2010-11-30 18:04:17 |
Message-ID: | AANLkTik9F9sm_o-F76Go1QdTkLK8Jn3d5QzNtE86ctZf@mail.gmail.com |
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Lists: | pgsql-hackers |
> 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 ?
Greets,
--
Daniel Loureiro
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