[mildbyte]

Have you seen duckdb_fdw (https://github.com/alitrack/duckdb_fdw)? IIRC it's built based on sqlite_fdw, but points the outbound queries to DuckDB instead of SQLite, and it does handle running aggregations inside of DuckDB. Could be useful.

[wanderinglight]

This is great, thank so much! I'll see if I can I can integrate this and how it compares to parquet_fdw.