Function create_context

datafusion-examples/examples/udf/simple_udwf.rs:33–78

create local execution context with `cars.csv` registered as a table named `cars`

()

// create local execution context with `cars.csv` registered as a table named `cars`
async fn create_context() -> Result<SessionContext> {
    // declare a new context. In spark API, this corresponds to a new spark SQL session
    let ctx = SessionContext::new();

    // content from file 'datafusion/core/tests/data/cars.csv'
    let csv_data = r#"car,speed,time
red,20.0,1996-04-12T12:05:03.000000000
red,20.3,1996-04-12T12:05:04.000000000
red,21.4,1996-04-12T12:05:05.000000000
red,21.5,1996-04-12T12:05:06.000000000
red,19.0,1996-04-12T12:05:07.000000000
red,18.0,1996-04-12T12:05:08.000000000
red,17.0,1996-04-12T12:05:09.000000000
red,7.0,1996-04-12T12:05:10.000000000
red,7.1,1996-04-12T12:05:11.000000000
red,7.2,1996-04-12T12:05:12.000000000
red,3.0,1996-04-12T12:05:13.000000000
red,1.0,1996-04-12T12:05:14.000000000
red,0.0,1996-04-12T12:05:15.000000000
green,10.0,1996-04-12T12:05:03.000000000
green,10.3,1996-04-12T12:05:04.000000000
green,10.4,1996-04-12T12:05:05.000000000
green,10.5,1996-04-12T12:05:06.000000000
green,11.0,1996-04-12T12:05:07.000000000
green,12.0,1996-04-12T12:05:08.000000000
green,14.0,1996-04-12T12:05:09.000000000
green,15.0,1996-04-12T12:05:10.000000000
green,15.1,1996-04-12T12:05:11.000000000
green,15.2,1996-04-12T12:05:12.000000000
green,8.0,1996-04-12T12:05:13.000000000
green,2.0,1996-04-12T12:05:14.000000000
"#;
    let dir = tempdir()?;
    let file_path = dir.path().join("cars.csv");
    {
        let mut file = File::create(&file_path)?;
        // write CSV data
        file.write_all(csv_data.as_bytes())?;
    } // scope closes the file
    let file_path = file_path.to_str().unwrap();

    ctx.register_csv("cars", file_path, CsvReadOptions::new())
        .await?;

    Ok(ctx)
}

/// In this example we will declare a user defined window function that computes a moving average and then run it using SQL
pub async fn simple_udwf() -> Result<()> {