On 2018-Dec-06, Amit Langote wrote:
> The partitionwise join related
> changes in PG 11 moved the add_child_rel_equivalences call in
> set_append_rel_size such that child EC members would be added even before
> checking if the child rel is dummy, but for a reason named in the comment
> above the call:
>
> ... Even if this child is
> * deemed dummy, it may fall on nullable side in a child-join, which
> * in turn may participate in a MergeAppend, where we will need the
> * EquivalenceClass data structures.
>
> However, I think we can skip adding the dummy child EC members here and
> instead make it a responsibility of partitionwise join code in joinrels.c
> to add the needed EC members. Attached a patch to show what I mean, which
> passes the tests and gives this planning time:
Robert, Ashutosh, any comments on this? I'm unfamiliar with the
partitionwise join code.
--
Álvaro Herrera https://www.2ndQuadrant.com/
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