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.etsuro@lab.ntt.co.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