Re: BUG #18261: Inconsistent results of SELECT affected by joined subqueries

Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> I've looked into it a bit. The problem lies in how the SJE code handles
> the transfer of qual clauses from the removed relation to the remaining
> one.

I am definitely starting to think that the SJE patch was not ready
for prime time. We keep finding not only minor but major problems
in it --- I'd call this one a "major" one. Is it time to revert
and rethink it from scratch?

> If we determine that avoiding duplicates is necessary, I think at least
> we should compare the entire RestrictInfos not just their clauses. One
> challenge with this approach is that the 'rinfo_serial' usually differs,
> making direct comparison problematic. I'm wondering if we can make
> 'rinfo_serial' equal_ignore. Not too sure about that.

I'd say that that will break the cases rinfo_serial was introduced for.
Now, I certainly don't love rinfo_serial and would be happier if we
could do without it, but getting rid of it is another research project.

regards, tom lane