On 2016/02/16 16:02, Ashutosh Bapat wrote:
On Tue, Feb 16, 2016 at 12:26 PM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp <mailto:fujita.ets...@lab.ntt.co.jp>> wrote:
On 2016/02/16 15:22, Ashutosh Bapat wrote:
During join planning, the planner tries multiple combinations of joining relations, thus the same base or join relation can be part of multiple of combination. Hence remote_conds or joinclauses will get linked multiple times as they are bidirectional lists, thus breaking linkages of previous join combinations tried. E.g. while planning A join B join C join D planner will come up with combinations like A(B(CD)) or (AB)(CD) or ((AB)C)D etc. and remote_conds from A will first be linked into A(B(CD)), then AB breaking the first linkages.
Exactly, but I don't think that that needs to be considered because we have this at the beginning of postgresGetGForeignJoinPaths: /* * Skip if this join combination has been considered already. */ if (joinrel->fdw_private) return;
There will be different joinrels for A(B(CD)) and (AB) where A's remote_conds need to be pulled up.
Agreed.
The check you have mentioned above only protects us from adding paths multiple times to (AB) when we encounter it for (AB)(CD) and ((AB)C)D.
Sorry, I don't understand this fully. 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