Re: Push down more full joins in postgres_fdw

On 2016/10/26 19:53, Ashutosh Bapat wrote:
> On Wed, Oct 26, 2016 at 3:35 PM, Etsuro Fujita
> <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> wrote:

>> In practice, the search cost would be negligible compared to the cost of
>> explaining/executing the query.
>>
>> My concern about your proposal is: it might not be worth complicating the
>> code to solve a problem that is actually not a problem in practice.

> To me the current code looks complicated esp. because of the recursion
> involved and usage of out parameters to isSubqueryExpr().

I don't think so. isSubqueryExpr is prety small, written in less than
50 lines, and the code looks rather simple to me.

> My
> suggestion goes inline with the current method of deparsing a Var.

Yeah, I think your approach makes it easy to search for the alias to a
given Var from the array you proposed. I think the complexity of your
approach would be in extra work for building and maintaining the array
while deparsing the query. I think that would probably need more
invasive and much larger changes to the existing code than what I proposed.

I think this issue is optional, so I'd like to propose to leave this for
the committer's judge.

Best regards,
Etsuro Fujita