nats_rw

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Read and write NATS JetStream streams with SQL

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.

Installing and Loading

INSTALL nats_rw FROM community;
LOAD nats_rw;

Example

-- Write query results to a NATS JetStream stream
COPY (SELECT 'hello' AS v) TO 'my_stream'
  (FORMAT nats_rw, url 'nats://localhost:4222', create_stream 'true');

-- Read it back
SELECT * FROM nats_rw_scan('my_stream', url := 'nats://localhost:4222');

-- Extract JSON fields as columns
SELECT device_id, location_zone
FROM nats_rw_scan('my_stream', url := 'nats://localhost:4222',
    json_extract := ['device_id', 'location.zone']);

About nats_rw

The nats_rw extension provides bidirectional NATS JetStream access from DuckDB:

• Read: nats_rw_scan() table function — bounded snapshot scan with subject filtering, sequence/time ranges, JSON field extraction, and predicate pushdown (WHERE seq/ts_nats automatically narrows the scan range)
• Write: COPY … TO '<stream>' (FORMAT nats_rw) — publish query results with optional payload_column, subject_prefix, and auto stream creation
• Auth: CREATE SECRET (TYPE nats_rw, …) — user/password, token, nkey, or credentials file, with scope-based auto-matching
• Metadata: nats_rw_streams() and nats_rw_stream_info() for inspection
• Performance: connection pooling (per-url cache) + predicate pushdown

Connections are cached per (url, auth) for efficient repeated queries.

Documentation: https://github.com/robert-guangzhou/duckdb-nats-rw

Added Functions

Overloaded Functions

This extension does not add any function overloads.

Added Types

This extension does not add any types.

Added Settings