Trait datafusion_common::ExprSchema

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pub trait ExprSchema: Debug {
    // Required methods
    fn nullable(&self, col: &Column) -> Result<bool>;
    fn data_type(&self, col: &Column) -> Result<&DataType>;
    fn metadata(&self, col: &Column) -> Result<&HashMap<String, String>>;
}
Expand description

Provides schema information needed by certain methods of Expr (defined in the datafusion-common crate).

Note that this trait is implemented for &DFSchema which is widely used in the DataFusion codebase.

Required Methods§

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fn nullable(&self, col: &Column) -> Result<bool>

Is this column reference nullable?

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fn data_type(&self, col: &Column) -> Result<&DataType>

What is the datatype of this column?

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fn metadata(&self, col: &Column) -> Result<&HashMap<String, String>>

Returns the column’s optional metadata.

Implementors§