Andres Freund <andres(at)anarazel(dot)de> writes:
> SELECT *
> FROM
> ab LEFT OUTER JOIN (
> bc JOIN cd
> ON bc.c = cd.d
> )
> ON ab.b = bc.b
> WHERE
> ab.a = 20000
> As ab.a = 20000 occurs only once in ab one would expect that it just does an
> index scan on bc for ab.b = bc.b.
The only way it could do that would be by interchanging the order of the
left and inner joins, ie (ab left join bc) join cd; which would change
the results.
I believe it could interchange the joins if they were both LEFT or
both INNER. Do you really need exactly these semantics?
regards, tom lane