DuckDB

Zero-config local analytics engine. db_type is duckdb. Supports local file databases, in-memory (:memory:), and MotherDuck cloud (md: URLs). Tier 3.

Connection config

duckdb

{
  "name": "local-duckdb",
  "db_type": "duckdb",
  "database": "/path/to/warehouse.duckdb"
}

MotherDuck:

motherduck

{
  "name": "motherduck",
  "db_type": "duckdb",
  "database": "md:my_database",
  "motherduck_token": "..."
}

Connection fields

Field	Required	Description
name	Yes	Connection name. [a-zA-Z0-9_-], max 64 chars.
db_type	Yes	duckdb.
database	Yes	File path to the .duckdb file, :memory:, or a md: MotherDuck URL.
motherduck_token	No	MotherDuck personal access token. Required for md: connections.
query_timeout	No	Seconds, 1–3600.

Capabilities

Capability	Supported	Notes
Query	Yes	File-based DBs open a transient read-only connection per query, so the gateway never holds a write lock that would block dbt. In-memory DBs use a persistent connection.
Schema introspection	Yes (full)	information_schema for columns/tables, duckdb_tables() / duckdb_columns() for comments and estimated sizes.
FK discovery	Yes	Via information_schema table constraints.
EXPLAIN	Yes	Supported.
Cost estimation	No	Not byte-billed.
Schema stats	Yes	Estimated row count from duckdb_tables().estimated_size; table and column comments.

Tier 3.

Dialect notes / gotchas

• Identifiers are quoted with double quotes ("col").
• Integer division truncates.
• INTERVAL syntax requires quotes.
• DATE_TRUNC returns a TIMESTAMP.
• File-based connections are opened read-only per query; dbt can take the write lock between MCP queries.

Blocked functions

These DuckDB functions are blocked inside SELECT (plus all DDL/DML):

• File system: read_csv, read_csv_auto, read_parquet, read_json, read_json_auto, read_blob, read_text
• Network: httpfs_get, http_get, http_post
• Cross-engine scanning: postgres_scan, sqlite_scan, mysql_scan, iceberg_scan, delta_scan
• Extension loading: load_extension, install_extension

The universal load_extension / install_extension block also applies.

Recommended plugin skill

duckdb-sql — covers DuckDB-specific patterns and gotchas that differ from PostgreSQL/MySQL.

Cloud vs local

DuckDB is a local connector: the gateway needs filesystem access to the .duckdb file. MotherDuck (md: URLs with a motherduck_token) provides a cloud-hosted DuckDB. When the sandbox service is enabled (SP_SANDBOX_ENABLED=true) in local mode, DuckDB runs through the sandboxed connector.