On 2016/09/27 13:33, Ashutosh Bapat wrote: I wrote:
ISTM that the use of the same RTI for subqueries in multi-levels in a remote SQL makes the SQL a bit difficult to read. How about using the position of the join rel in join_rel_list, (more precisely, the position plus list_length(root->parse->rtable)), instead?
I wrote:
The join rel is appended to the end of the list, so I was thinking to get the position info by list_length during postgresGetForeignJoinPaths.
That's true only when the paths are being added to a newly created joinrel. But that's not true always. We may add paths with different joining order to an existing joinrel, in which case list_length would not give its position. Am I missing something?
I think you are right, but postgresGetForeignJoinPaths only allows us to add a foreign join path to a newly created joinrel. The reason is because that routine skips all its work after the first call for that joinrel, by checking to see if joinrel->fdw_private is not NULL. So, I think it's reasonable to get the position by list_length in that routine.
Best regards, Etsuro Fujita -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
