Re: OUTER joins

From: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
To: lockhart(at)alumni(dot)caltech(dot)edu (Thomas G(dot) Lockhart)
Cc: hackers(at)postgreSQL(dot)org
Subject: Re: OUTER joins
Date: 1999-03-09 03:25:41
Message-ID: 199903090325.WAA16653@candle.pha.pa.us
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> > > Hadn't thought about it, other than figuring that implementing the
> > > equi-join first was a good start. There is a class of outer join
> > > syntax (the USING clause) which is implicitly an equi-join...
> > Not that easy. You don't automatically get a mergejoin from an
> > equijoin. I will have to force outer's to be either mergejoins, or
> > inners of non-merge joins. Can you add code to non-merge joins in the
> > executor to throw out a null row if it does not find an inner match
> > for the outer row, and I will handle the optimizer so it doesn't throw
> > a non-conforming plan to the executor.
>
> So far I don't have enough info in the parser to get the
> planner/optimizer going. Should we work from the front to the back, or
> should I go ahead and look at the non-merge joins? It's painfully
> obvious that I don't know anything about the middle parts of this to
> proceed without lots more research.

We need to do phone or IRC to discuss this. Let me know when.

--
Bruce Momjian | http://www.op.net/~candle
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