- Adapted `pgmerge.sql` tests from PostgreSQL community's `merge.sql` to
Citus by converting tables into Citus local tables.
- Identified two new PostgreSQL 17 MERGE features (`RETURNING` support
and MERGE on updatable views) not yet supported by Citus.
- Implemented changes to detect unsupported features and raise clean
exceptions, ensuring pgmerge tests pass without diffs.
- Addressed breaking changes caused by `MERGE ... WHEN NOT MATCHED BY
SOURCE` restructuring, reducing diffs in pgmerge tests.
- Segregated unsupported test cases into `merge_unsupported.sql` to
maintain clarity and avoid large diffs in test files.
- Prepared the Citus MERGE planner to handle new PostgreSQL changes,
reducing remaining test discrepancies.
All merge tests now pass cleanly, with unsupported cases clearly
isolated.
Relevant PG commits:
c649fa24a
https://github.com/postgres/postgres/commit/c649fa24a
0294df2f1
https://github.com/postgres/postgres/commit/0294df2f1
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Co-authored-by: naisila <nicypp@gmail.com>