pgsql: Improve create_unique_path to not be fooled by unrelated clauses

From: tgl(at)postgresql(dot)org (Tom Lane)
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Improve create_unique_path to not be fooled by unrelated clauses
Date: 2009-02-27 00:06:28
Message-ID: 20090227000628.193237559ED@cvs.postgresql.org
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Log Message:
-----------
Improve create_unique_path to not be fooled by unrelated clauses that happen
to be syntactically part of a semijoin clause. For example given
WHERE EXISTS(SELECT ... WHERE upper.var = lower.var AND some-condition)
where some-condition is just a restriction on the lower relation, we can
use unique-ification on lower.var after having applied some-condition within
the scan on lower.

Modified Files:
--------------
pgsql/src/backend/optimizer/util:
pathnode.c (r1.149 -> r1.150)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/pathnode.c?r1=1.149&r2=1.150)

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