Arrow User-Defined Functions Framework

Easily create and run user-defined functions (UDF) on Apache Arrow. You can define functions in Rust, Python, Java or JavaScript. The functions can be executed natively, or in WebAssembly, or in a remote server.

Language	Native	WebAssembly	Remote
Rust	arrow-udf	arrow-udf-wasm
Python	arrow-udf-python		arrow-udf-flight/python
JavaScript	arrow-udf-js or arrow-udf-js-deno
Java			arrow-udf-flight/java

Extension Types

In addition to the standard types defined by Arrow, these crates also support the following data types through Arrow's extension type. When using extension types, you need to add the ARROW:extension:name key to the field's metadata.

Extension Type	Physical Type	Metadata
JSON	Utf8	ARROW:extension:name = arrowudf.json
Decimal	Utf8	ARROW:extension:name = arrowudf.decimal

JSON Type

JSON type is stored in string array in text form.

let json_field = Field::new(name, DataType::Utf8, true)
    .with_metadata([("ARROW:extension:name".into(), "arrowudf.json".into())].into());
let json_array = StringArray::from(vec![r#"{"key": "value"}"#]);

Decimal Type

Different from the fixed-point decimal type built into Arrow, this decimal type represents floating-point numbers with arbitrary precision or scale, that is, the unconstrained numeric in Postgres. The decimal type is stored in a string array in text form.

let decimal_field = Field::new(name, DataType::Utf8, true)
    .with_metadata([("ARROW:extension:name".into(), "arrowudf.decimal".into())].into());
let decimal_array = StringArray::from(vec!["0.0001", "-1.23", "0"]);

Benchmarks

We have benchmarked the performance of function calls in different environments. You can run the benchmarks with the following command:

cargo bench --bench wasm

Performance comparison of calling gcd on a chunk of 1024 rows:

gcd/native          1.5237 µs   x1
gcd/wasm            15.547 µs   x10
gcd/js(quickjs)     85.007 µs   x55
gcd/js(deno)        93.584 µs   x62
gcd/python          175.29 µs   x115

Who is using this library?

• RisingWave: A Distributed SQL Database for Stream Processing.