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;
Best regards,
Etsuro Fujita
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