Deprecated: The each() function is deprecated. This message will be suppressed on further calls in /home/zhenxiangba/zhenxiangba.com/public_html/phproxy-improved-master/index.php on line 456
ExprSchema in datafusion::common - Rust
[go: Go Back, main page]

Trait datafusion::common::ExprSchema

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

source

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

Is this column reference nullable?

source

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

What is the datatype of this column?

source

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

Returns the column’s optional metadata.

Implementors§