DuckDB SQL Reference for MotherDuck

Use this skill when you need exact DuckDB syntax, function behavior, or a quick sanity check that a statement will actually work on MotherDuck.

Source Of Truth

Prefer current DuckDB SQL docs for language features and function semantics.
Use current MotherDuck SQL docs for MotherDuck-only commands such as shares, secrets, snapshots, and Dive operations.
If the connection path matters, verify behavior against the current Postgres-endpoint docs before promising server-mode support.

Write DuckDB SQL, not PostgreSQL SQL, even when the client connects through the Postgres endpoint.
Use fully qualified "database"."schema"."table" names once more than one database or share is in scope.
Prefer DuckDB-native constructs when they simplify the query: GROUP BY ALL, QUALIFY, UNION BY NAME, arg_max, EXCLUDE, and REPLACE.
Check whether the statement depends on local files, extension install/load, temporary-table behavior, or other client-only features before claiming it will work in MotherDuck.
Treat MotherDuck SQL as an additional surface on top of DuckDB SQL, not a replacement for it.