Richard Guo <guofenglinux@gmail.com> writes:
> On Thu, Apr 9, 2020 at 1:07 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I have hopes of being able to incorporate outer
>> joins into the EC logic in a less squishy way in the future, by making
>> the representation of Vars distinguish explicitly between
>> value-before-outer-join and value-after-outer-join, after which we could
>> make bulletproof assertions about what is equal to what, even with outer
>> joins in the mix. If that works out it might produce a cleaner answer
>> in this area too.
> This is very appealing. Do we have ongoing discussions/threads about
> this idea?
There's some preliminary noodling in this thread:
https://www.postgresql.org/message-id/flat/15848.1576515643%40sss.pgh.pa.us
I've pushed the earlier work discussed there, but stalled out due to
the call of other responsibilities after posting the currently-last
message in the thread. Hoping to get back into that over the summer.
regards, tom lane