OUTER joins

How do you propose doing outer joins in non-mergejoin situations?
Mergejoins can only be used currently in equal joins.

Is your solution going to be to make sure the OUTER table is always a
MergeJoin, or on the outside of a join loop? That could work.

That could get tricky if the table is joined to _two_ other tables.
With the cleaned-up optimizer, we can disable non-merge joins in certain
circumstances, and prevent OUTER tables from being inner in the others.
Is that the plan?

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

(back from a short vacation...)

How do you propose doing outer joins in non-mergejoin situations?
Mergejoins can only be used currently in equal joins.

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...

- Tom

(back from a short vacation...)

How do you propose doing outer joins in non-mergejoin situations?
Mergejoins can only be used currently in equal joins.

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.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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.

- Tom

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
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026