Re: BUG #12000: "CROSS JOIN" not equivalent to ","

David Johnston <david.g.johnston@gmail.com> writes:
> On Tuesday, November 18, 2014, Alvaro Herrera <alvherre@2ndquadrant.com>
> wrote:
>> Note that using explicit join form force the optimizer into some
>> specific join order, depending on the join_collapse_limit parameter,
>> whereas using commas gives it absolute freedom regardless of the
>> parameter.

> Only because the parameter used in that case is "from_collapse_limit"...

IIRC, from_collapse_limit only affects the behavior when deciding whether
to collapse a mixture of JOIN and comma syntax; it does not change the
outcome if you write a whole bunch of tables in a comma-separated list to
start with.

In any case, such implementation artifacts shouldn't drive our
consideration of what's the clearest way to document this SQL-standard
behavior.

            regards, tom lane