ondatrasql

README

OndatraSQL

A data pipeline runtime for DuckDB and DuckLake
Ingestion, transformation, validation, and scheduling in a single binary.

Documentation · Discord · Blueprints

---

OndatraSQL runs data pipelines using SQL models, DuckDB for query execution, and DuckLake for catalog management, snapshots, and time-travel.

The runtime handles:

• Dependency resolution — extracted from SQL references
• Change detection — via DuckLake snapshots and table_changes()
• Schema evolution — columns added, renamed, or type-promoted automatically
• Validation — constraints, audits, and warnings as part of execution
• Incremental processing — Smart CDC rewrites queries to process only changed data

Install

curl -fsSL https://ondatra.sh/install.sh | sh

Supports Linux, macOS, and Windows via WSL2.

Quick Start

mkdir my-pipeline && cd my-pipeline
ondatrasql init

Ingest data from an API (create a blueprint in lib/):

# lib/countries_fetch.star
API = {
    "base_url": "https://restcountries.com",
    "fetch": {
        "args": [],
    },
}

def fetch(page):
    resp = http.get("/v3.1/region/europe")
    rows = [{"name": c["name"]["common"], "capital": c["capital"][0], "population": c["population"]} for c in resp.json]
    return {"rows": rows, "next": None}

-- models/raw/countries.sql
-- @kind: table
SELECT * FROM countries_fetch()

Transform with SQL:

ondatrasql new staging.countries.sql
ondatrasql edit staging.countries.sql

-- @kind: table
-- @constraint: not_null(name)

SELECT
    name, capital, population,
    CASE
        WHEN population > 50000000 THEN 'large'
        WHEN population > 10000000 THEN 'medium'
        ELSE 'small'
    END AS size
FROM raw.countries

Run the pipeline:

ondatrasql run

Running 2 models...
[OK] raw.countries      (table, backfill, 53 rows, 1.1s)
[OK] staging.countries  (table, backfill, 53 rows, 250ms — first run)

Done: 2 ran, 0 skipped, 0 failed (106 rows, 1.4s)

Model Types

SQL — transformations:

-- @kind: table

SELECT date, SUM(total) AS revenue
FROM staging.orders GROUP BY date

Lib functions — API ingestion and outbound sync via Starlark in lib/:

-- models/raw/users.sql
-- @kind: table
SELECT * FROM my_api('users')

# lib/my_api.star — fetch function called by the SQL model
API = {"base_url": "https://api.example.com", "auth": {"env": "API_KEY"},
       "fetch": {"args": ["resource"], "page_size": 100}}

def fetch(resource, page):
    resp = http.get("/v1/" + resource, params={"limit": page.size, "cursor": page.cursor})
    return {"rows": resp.json["items"], "next": resp.json.get("next")}

Models are SQL files. Starlark is used in lib/ for API transport (HTTP, auth, pagination).

All models execute in the same pipeline and share the same dependency graph.

Key Capabilities

Capability	How it works
SQL transformation	SQL models with automatic materialization and CDC
API ingestion	Built-in HTTP, OAuth, pagination via Starlark
Event collection	Embedded HTTP endpoint with in-memory and durable buffering
Outbound sync	Push to APIs via @sink with raw DuckLake change types
Validation	30 constraint macros, 18 audit macros, 14 warning macros
Schema evolution	Automatic via ALTER TABLE (metadata-only in DuckLake)
Sandbox preview	Full DAG simulation before committing
Scheduling	OS-native cron via systemd (Linux) or launchd (macOS)
OData serving	Built-in OData v4 server for Power BI, Excel, Grafana
Column lineage	Extracted from SQL AST

Design

OndatraSQL executes on a single machine using DuckDB. It is not a distributed system. For workloads that fit on one machine — batch ETL, reporting, analytics, internal tooling — this approach provides the full pipeline lifecycle with minimal operational overhead.

Commands

run [model]          Execute pipeline or specific model
sandbox [model]      Preview changes before committing
schedule [cron]      Install OS-native scheduler
odata <port>         Start OData v4 server
events <port>        Start event collection endpoint
auth [provider]      Authenticate with OAuth2 providers
new <model>          Create a model file
edit <target>        Open file in $EDITOR
sql "SELECT ..."     Query DuckLake catalog
stats                Project overview
describe <model>     Model details and schema
history [model]      Run history
lineage overview     View dependencies and column lineage
flush                Flush inlined data to Parquet
checkpoint           Run all maintenance

Full CLI reference →

Documentation

ondatra.sh

License

GNU AGPL v3