pgsql: Don't pass down nonnullable_vars while reducing outer joins.

Don't pass down nonnullable_vars while reducing outer joins.

We weren't actually using the passed-down list for anything, other
than computing the new value to be passed down further. I (tgl)
probably had the idea that we'd need this data eventually; but
no use-case has emerged in a good long while, so let's just stop
expending useless cycles here.

Richard Guo

Discussion: https://postgr.es/m/CAMbWs48KLy9aBb=sZ5MoNmnqAcGHaW_JTGWLCgoE_uMW7S6C-A@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b0b72c64a0ce7bf5dd78a80b33d85c89c943ad0d

Modified Files
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src/backend/optimizer/prep/prepjointree.c | 33 ++++++-------------------------
1 file changed, 6 insertions(+), 27 deletions(-)