DataFusion

DataFusion is an in-memory query engine that uses Apache Arrow as the memory model. It supports executing SQL queries against CSV and Parquet files as well as querying directly against in-memory data.

Usage

Use as a lib

Add this to your Cargo.toml:

[dependencies]
datafusion = "0.15.1"

Use as a bin

Build your own bin(requires rust toolchains)

git clone https://github/apache/arrow
cd arrow/rust/datafusion
cargo run --bin datafusion-cli

Use Dockerfile

git clone https://github.com/apache/arrow
cd arrow
docker build -f rust/datafusion/Dockerfile . --tag datafusion-cli
docker run -it -v $(your_data_location):/data datafusion-cli

USAGE:
    datafusion-cli [OPTIONS]

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
    -c, --batch-size <batch-size>    The batch size of each query, default value is 1048576
    -p, --data-path <data-path>      Path to your data, default to current directory

Status

General

• [x] SQL Parser
• [x] SQL Query Planner
• [x] Query Optimizer
• [x] Projection push down
• [ ] Predicate push down
• [x] Type coercion
• [ ] Parallel query execution

SQL Support

• [x] Projection
• [x] Selection
• [x] Aggregate
• [ ] Sorting
• [x] Limit
• [ ] Nested types and dot notation
• [ ] Lists
• [ ] UDFs
• [ ] Subqueries
• [ ] Joins

Data Sources

• [x] CSV
• [x] Parquet primitive types
• [ ] Parquet nested types

Example

Here is a brief example for running a SQL query against a CSV file. See the examples directory for full examples.

fn main() {
    // create local execution context
    let mut ctx = ExecutionContext::new();

    // define schema for data source (csv file)
    let schema = Arc::new(Schema::new(vec![
        Field::new("c1", DataType::Utf8, false),
        Field::new("c2", DataType::UInt32, false),
        Field::new("c3", DataType::Int8, false),
        Field::new("c4", DataType::Int16, false),
        Field::new("c5", DataType::Int32, false),
        Field::new("c6", DataType::Int64, false),
        Field::new("c7", DataType::UInt8, false),
        Field::new("c8", DataType::UInt16, false),
        Field::new("c9", DataType::UInt32, false),
        Field::new("c10", DataType::UInt64, false),
        Field::new("c11", DataType::Float32, false),
        Field::new("c12", DataType::Float64, false),
        Field::new("c13", DataType::Utf8, false),
    ]));

    // register csv file with the execution context
    let csv_datasource = CsvDataSource::new(
        "../../testing/data/csv/aggregate_test_100.csv",
        schema.clone(),
        1024,
    );
    ctx.register_datasource("aggregate_test_100", Rc::new(RefCell::new(csv_datasource)));

    // execute the query
    let sql = "SELECT c1, MIN(c12), MAX(c12) FROM aggregate_test_100 WHERE c11 > 0.1 AND c11 < 0.9 GROUP BY c1";
    let relation = ctx.sql(&sql).unwrap();
    let mut results = relation.borrow_mut();

    // iterate over result batches
    while let Some(batch) = results.next().unwrap() {
        println!(
            "RecordBatch has {} rows and {} columns",
            batch.num_rows(),
            batch.num_columns()
        );

        let c1 = batch
            .column(0)
            .as_any()
            .downcast_ref::<BinaryArray>()
            .unwrap();

        let min = batch
            .column(1)
            .as_any()
            .downcast_ref::<Float64Array>()
            .unwrap();

        let max = batch
            .column(2)
            .as_any()
            .downcast_ref::<Float64Array>()
            .unwrap();

        for i in 0..batch.num_rows() {
            let c1_value: String = String::from_utf8(c1.value(i).to_vec()).unwrap();

            println!("{}, Min: {}, Max: {}", c1_value, min.value(i), max.value(i),);
        }
    }
}