Re: FULL JOIN is only supported with merge-joinable join conditions

"hx.li" <fly2nn@126.com> writes:
> ERROR:  FULL JOIN is only supported with merge-joinable join conditions
> My question is: why on clause restrict "t_1.a=1"?

It's an implementation restriction.  If the clauses aren't mergejoinable
there's no very practical way to keep track of which inner-side rows
have had a match.

> I test it in Oracle, it support to such as "t_1.a=1":

I'd be interested to know how whatever they're doing scales to very
large joins.

            regards, tom lane