Function evaluate_expr_with_null_column

datafusion/optimizer/src/utils.rs:162–187

(
    predicate: Expr,
    null_columns: impl IntoIterator<Item = &'a Column>,
)

}

fn evaluate_expr_with_null_column<'a>(
    predicate: Expr,
    null_columns: impl IntoIterator<Item = &'a Column>,
) -> Result<ColumnarValue> {
    static DUMMY_COL_NAME: &str = "?";
    let schema = Arc::new(Schema::new(vec![Field::new(
        DUMMY_COL_NAME,
        DataType::Null,
        true,
    )]));
    let input_schema = DFSchema::try_from(Arc::clone(&schema))?;
    let column = new_null_array(&DataType::Null, 1);
    let input_batch = RecordBatch::try_new(schema, vec![column])?;
    let execution_props = ExecutionProps::default();
    let null_column = Column::from_name(DUMMY_COL_NAME);

    let join_cols_to_replace = null_columns
        .into_iter()
        .map(|column| (column, &null_column))
        .collect::<HashMap<_, _>>();

    let replaced_predicate = replace_col(predicate, &join_cols_to_replace)?;
    let coerced_predicate = coerce(replaced_predicate, &input_schema)?;
    create_physical_expr(&coerced_predicate, &input_schema, &execution_props)?
        .evaluate(&input_batch)
}

fn coerce(expr: Expr, schema: &DFSchema) -> Result<Expr> {
    let mut expr_rewrite = TypeCoercionRewriter { schema };