Query MotherDuck

Use this skill when executing SQL queries for analytics, aggregations, transformations, or data exploration against MotherDuck databases.

Prerequisites

• MotherDuck connection established via

  motherduck-connect

• Target database and tables identified via

  motherduck-explore

Default Posture

• Write DuckDB SQL, not PostgreSQL SQL, even when using the PG endpoint.
• Always use fully qualified

  "database"."schema"."table"

  names.
• Filter early, aggregate early, and prefer serving tables or summaries for repeated reads.
• Keep SQL obvious, multi-line, and explicit about grain, filters, and output shape.
• Treat DDL, DML,

  ATTACH

  ,

  DETACH

  , and lifecycle commands such as

  SHUTDOWN

  as writes. Use MCP

  query_rw

  only when the user explicitly asks for the change and confirms it.
• Tag long-lived integrations with

  custom_user_agent

  when the connection path supports it.

Workflow

1. Confirm the actual tables, columns, and grain before writing SQL.
2. Write the query in SQL first, then wrap it in Python or TypeScript only if needed.
3. Use CTEs and DuckDB-native patterns such as

   GROUP BY ALL

   ,

   QUALIFY

   , and

   arg_max

   .
4. Check the plan and shape for pushdown, unnecessary sorts, or repeated raw rescans.
5. Materialize expensive repeated queries into serving tables or light views when warranted.

Open Next

• references/QUERY_PLAYBOOK.md

  for DuckDB query patterns, exploration SQL, performance rules, common analytical shapes, and common mistakes

Related Skills

• motherduck-connect

  for session setup

• motherduck-duckdb-sql

  for syntax and function reference

• motherduck-explore

  for understanding the source schema before writing queries