Re: Minor ON CONFLICT related fixes

On Mon, May 11, 2015 at 7:34 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> You should try to understand why it's failing. Just prohibiting the
> rules, without understanding what's actually going on, could very well
> hide a real bug.

It's not as if I have no idea. ReplaceVarsFromTargetList() is probably
quite confused by all this, because the passed nomatch_varno argument
is often rt_index -- but what about EXCLUDED.*? adjustJoinTreeList()
does not know anything about EXCLUDED.* either. I see little practical
reason to make the rewriter do any better.

When I debugged the problem of the optimizer raising that "target
lists" error with a rule with an action with EXCLUDED.* (within
setrefs.c's fix_join_expr_mutator()), it looked like an off-by-one
issue here:

/* If it's for acceptable_rel, adjust and return it */
if (var->varno == context->acceptable_rel)
{
var = copyVar(var);
var->varno += context->rtoffset;
if (var->varnoold > 0)
var->varnoold += context->rtoffset;
return (Node *) var;
}

--
Peter Geoghegan