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mongo
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Extension descriptor (YAML)

Integrates DuckDB with MongoDB, enabling direct SQL queries and writes over MongoDB collections without ETL

Maintainer(s): stephaniewang526

Compatibility Matrix

This table covers all DuckDB releases that have not reached end-of-life, including LTS releases, and shows the 2 most recent patch releases of each. Older patch releases are not listed, but the extension may be available for them as well.

Platform 1.4.4 1.4.5 1.5.5 1.5.6 2.0.0
Linux AMD64
Linux ARM64
macOS AMD64
macOS ARM64
Windows AMD64
Windows ARM64
WebAssembly

Installing and Loading 

INSTALL mongo FROM community;
LOAD mongo;

Example 

-- Attach to MongoDB
ATTACH 'host=localhost port=27017' AS mongo_db (TYPE MONGO);

-- Query collections with SQL
SELECT * FROM mongo_db.mydb.mycollection LIMIT 10;

-- Load a CSV directly into MongoDB
INSERT INTO mongo_db.mydb.mycollection
SELECT * FROM read_csv('data.csv');

About mongo

The duckdb-mongo extension provides direct SQL access to MongoDB collections without requiring data export or ETL processes. It supports both standalone MongoDB instances and MongoDB Atlas clusters.

Reading data:

  • Automatic schema inference from sampled documents, with nested document flattening
  • User-provided schemas and Atlas SQL __schema document support
  • Query pushdown to MongoDB for filters, projections, limits, TopN, and aggregations (COUNT, SUM, MIN, MAX, AVG)
  • BSON type mapping including ObjectId, Decimal128, arrays, and nested documents

Writing data (new in v0.3.0):

  • INSERT INTO – insert rows from any DuckDB source (CSV, Parquet, other databases, subqueries)
  • CREATE TABLE AS SELECT – create new MongoDB collections from query results
  • COPY TO (FORMAT mongo) – bulk-load data into MongoDB collections
  • DROP TABLE – drop MongoDB collections

Connections and security:

  • MongoDB Atlas support via connection strings or DuckDB Secrets
  • TLS/SSL encryption, custom CA certificates
  • mongo_enable_direct_scan setting to restrict mongo_scan to attached catalogs only

For detailed setup and usage instructions, visit the extension repository.

Added Functions

function_name function_type description comment examples
mongo_clear_cache table Clears the schema cache for all attached MongoDB databases. Useful when MongoDB schema changes. NULL [SELECT * FROM mongo_clear_cache()]
mongo_scan table Scans a MongoDB collection and returns its contents as a table. Supports optional filter and sample_size parameters. NULL [SELECT * FROM mongo_scan('mongodb://localhost:27017', 'mydb', 'mycollection'), SELECT * FROM mongo_scan('mongodb://localhost:27017', 'mydb', 'mycollection', filter := '{"status": "active"}')]

Overloaded Functions

This extension does not add any function overloads.

Added Types

This extension does not add any types.

Added Settings

name description input_type scope aliases
mongo_enable_direct_scan Allow mongo_scan to use a connection string that is not from an attached MongoDB database. When false, mongo_scan is only allowed if the connection string exactly matches an attached Mongo catalog. BOOLEAN GLOBAL []