Thread: pgsql: Disallow MERGE cleanly for foreign partitions

Disallow MERGE cleanly for foreign partitions

While directly targetting a foreign table with MERGE was already
expressly forbidden, we failed to catch the case of a partitioned table
that has a foreign table as a partition; and the result if you try is an
incomprehensible error.  Fix that by adding a specific check.

Backpatch to 15.

Reported-by: Tatsuhiro Nakamori <bt22nakamorit@oss.nttdata.com>
Discussion: https://postgr.es/m/bt22nakamorit@oss.nttdata.com

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/16d11d68437a6a37af1fea08d4a29ef463f0d62c

Modified Files
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contrib/postgres_fdw/expected/postgres_fdw.out |  5 +++++
contrib/postgres_fdw/sql/postgres_fdw.sql      |  4 ++++
src/backend/optimizer/plan/createplan.c        | 20 ++++++++++++++++++++
3 files changed, 29 insertions(+)