The following query: SELECT * FROM ( SELECT 2023 AS year, * FROM remote_table_1 UNION ALL SELECT 2022 AS year, * FROM remote_table_2 ) ORDER BY year DESC;
yields the following remote query: SELECT [columns] FROM remote_table_1 ORDER BY 2023 DESC and subsequently fails remote execution. Not really sure where the problem is - the planner or postgres_fdw. I guess it is postgres_fdw not filtering out ordering keys. This filtering would also be pretty useful in the following scenario (which is also why I went through UNION ALL route and discovered this issue): I have a table partitioned by year, partitions are remote tables. On remote servers I have a GIST index that does not support ordering ([1]) so I would like to avoid sending ORDER BY year to remote servers. Ideally redundant ordering should be filtered out. [1] https://www.postgresql.org/message-id/B2AC13F9-6655-4E27-BFD3-068844E5DC91%40kleczek.org — Kind regards, Michal
