Re: Parameterized-path cost comparisons need some work

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Apr 17, 2012 at 3:05 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Personally, I find required_outer more clear.  YMMV.

>> Perhaps.  What's bothering me is the potential for confusion with outer
>> joins; the parameter-supplying rels are *not* necessarily on the other
>> side of an outer join.  Anybody else have an opinion about that?

> Well, we also use the words "inner" and "outer" to refer to the sides
> of any join, regardless of type.

True.

>  The thing I don't like about "param_relids" is that "param" can refer
> to an awful lot of different things.

Fair enough.  I'll leave required_outer alone then, and adjust some
names in the new patch to be consistent with that.

As far as the other naming issue goes, it struck me that instead of
join_clause_is_parameterizable_xxx, we could call those functions
join_clause_is_movable_xxx, assuming it's okay to commandeer
the notion of "movable" for this particular usage.  It seems a bit
less generic than "parameterizable" anyway.  The "for" and "within"
bits don't fit with that though.  The first one could reasonably
be called "join_clause_is_movable_to", since we're checking if it's
okay to push the clause to precisely that base relation, but I'm a
bit at a loss for a modifier for the other one.  "into" would be
appropriate, but "to" and "into" are so close together that people
might get confused.
        regards, tom lane