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Extension descriptor (YAML)

Query NATS JetStream message streams directly 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_js FROM community;
LOAD nats_js;

Example

-- Read messages from a stream (the server defaults to nats://localhost:4222)
SELECT subject, seq, ts_nats, payload
FROM nats_scan('telemetry', start_seq := 1, end_seq := 100);

-- Filter subjects with NATS wildcards and extract JSON fields, including nested ones
SELECT seq, device_id, location_zone, kw
FROM nats_scan('telemetry',
    subject := 'telemetry.*.power.>',
    json_extract := ['device_id', 'location.zone', 'kw']
);

-- Extract Protocol Buffers fields with native types
SELECT device_id, location_zone, metrics_kw
FROM nats_scan('telemetry_proto',
    proto_file := 'telemetry.proto',
    proto_message := 'Telemetry',
    proto_extract := ['device_id', 'location.zone', 'metrics.kw']
);

About nats_js

The nats_js extension reads the messages stored in NATS JetStream streams with SQL. It creates no consumers.

Features:

• Subject filters with NATS wildcards, applied by the server
• Sequence ranges (start_seq, end_seq) and time ranges (start_time, end_time)
• JSON field extraction with dot paths for nested fields
• Protocol Buffers decoding from a .proto file at query time, with native DuckDB types
• Streams with or without allow_direct

Documentation: https://github.com/brannn/duckdb-nats-jetstream

Added Functions

Overloaded Functions

This extension does not add any function overloads.

Added Types

This extension does not add any types.

Added Settings