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planner & target lists

From: "Hicham G(dot) Elmongui" <elmongui(at)cs(dot)purdue(dot)edu>
To: <pgsql-hackers(at)postgresql(dot)org>
Subject: planner & target lists
Date: 2004-09-24 13:22:29
Message-ID: 200409241322.i8ODMTqS010873@newman.cs.purdue.edu (view raw or flat)
Thread:
Lists: pgsql-hackers
Hi,
I am confused about an internal point of the planner.

Consider a select query and the output target list at the root of the tree.
This target lists points to some Vars. Each of which has as relation either
INNER/OUTER.
Does this INNER/OUTER refer to the inner/outer relations of the top-most
node in the tree or to the bottom-most one.

In other words, in the following tree, a variable in B that shows in Op1's
target list, does it have its relation as INNER (which is B) or OUTER (which
is Op2)

         Op1
         / \
        /   \
       /     \
     Op2     Op3
     / \     / \
    /   \   /   \
   A     B C     D

Regards,
--h


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