Hi, thank you for your kind replay.
>> Would you hit upon any other work arounds?
>
>Have you considered not using the sub-select expression in the UPDATE targetlist? That is, doesn't the following query, which doesn't use the subquery expression, do the same job as the original >query:
>
>update a set a = wk.x::char(10), b = wk.x, c = wk.y from b wk where wk.x = a.b and a.a = '2017';
Thank you, it seems work in my test cases.
I misunderstood that SubLink (and following SubPlan) is always made
from update on a partitioned table,
but it actually made from subquery in update target list.
Regards.
Takeshi Ideriha