Hi, If the main motivation is better completion, with compatibility with DuckDB and ClickHouse as an additional benefit, v1 seems like the better choice.
With v1, FROM establishes the relation scope before SELECT, allowing psql to complete input columns. The select list then defines output aliases before GROUP BY and ORDER BY, where PostgreSQL permits those aliases. This gives us another useful completion opportunity. v2 loses this property for GROUP BY. v1 also matches the existing FROM-first syntax in DuckDB and ClickHouse. I think we should also test completion with JOINs: multiple relations, table aliases, qualified columns, ON/USING, and target-list columns from both sides. The current rules seem mostly centered on a single relation. Best regards, Denis Smirnov
