Struct CastExpr 

pub struct CastExpr {
    pub expr: Arc<dyn PhysicalExpr>,
    /* private fields */
}

CAST expression casts an expression to a specific data type and returns a runtime error on invalid cast

Fields

expr: Arc<dyn PhysicalExpr>

The expression to cast

Implementations

impl CastExpr

pub fn new( expr: Arc<dyn PhysicalExpr>, cast_type: DataType, cast_options: Option<CastOptions<'static>>, ) -> Self

Create a new CastExpr using only a DataType.

This constructor creates a type-only cast where metadata and nullability are passed through from the source expression (with extension type keys stripped from metadata). This is the most common use case when you only need to change the data type.

For explicit control over the output field’s metadata and nullability, use CastExpr::new_with_target_field or the individual builder methods.

pub fn new_with_target_field( expr: Arc<dyn PhysicalExpr>, target_field: FieldRef, cast_options: Option<CastOptions<'static>>, ) -> Self

Create a new CastExpr with an explicit target FieldRef.

The provided target_field determines the output characteristics:

• The field’s data type becomes the cast target type
• The field’s metadata is used exactly as provided
• The field’s nullability is preserved

This is the preferred constructor when the caller has explicit field information that should be used exactly (for example, during schema enforcement or adapter layers).

See CastExpr::new for type-only casts where source metadata should pass through.

pub fn expr(&self) -> &Arc<dyn PhysicalExpr>

The expression to cast

pub fn cast_type(&self) -> &DataType

The data type to cast to

pub fn target_metadata(&self) -> Option<&HashMap<String, String>>

Explicit metadata for the output field, or None to pass through source metadata.

pub fn target_nullable(&self) -> Option<bool>

Explicit nullability for the output field, or None to pass through source nullability.

pub fn target_field(&self) -> &FieldRef

The target field this cast was constructed with.

For a type-only cast this is a field synthesized from the target data type alone; only its data type is meaningful. Note that the returned field may not match what return_field() returns when evaluated against a schema, since return_field() may incorporate source field information.

Prefer cast_type(), target_metadata(), and target_nullable() for direct access to the individual components.

pub fn cast_options(&self) -> &CastOptions<'static>

The cast options

pub fn has_explicit_metadata(&self) -> bool

Whether this cast has explicit metadata (vs pass-through from source).

pub fn has_explicit_nullability(&self) -> bool

Whether this cast has explicit nullability (vs pass-through from source).

pub fn check_bigger_cast(cast_type: &DataType, src: &DataType) -> bool

Check if casting from the specified source type to the target type is a widening cast (e.g. from Int8 to Int16).

pub fn is_bigger_cast(&self, src: &DataType) -> bool

Check if the cast is a widening cast (e.g. from Int8 to Int16).

impl CastExpr

pub fn try_from_proto( node: &PhysicalExprNode, ctx: &PhysicalExprDecodeCtx<'_>, ) -> Result<Arc<dyn PhysicalExpr>>

Available on crate feature proto only.

Reconstruct a CastExpr from its protobuf representation.

Takes the whole PhysicalExprNode so the decode signature matches other migrated expressions and can inspect outer-node metadata if needed in the future.

Trait Implementations

impl Clone for CastExpr

fn clone(&self) -> CastExpr

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CastExpr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for CastExpr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for CastExpr

impl Hash for CastExpr

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for CastExpr

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PhysicalExpr for CastExpr

fn get_properties(&self, children: &[ExprProperties]) -> Result<ExprProperties>

A CastExpr preserves the ordering of its child if the cast is done under the same datatype family.

fn data_type(&self, _input_schema: &Schema) -> Result<DataType>

Get the data type of this expression, given the schema of the input. Returns an error if the data type cannot be determined, ex. if the schema is missing a required field.

fn nullable(&self, input_schema: &Schema) -> Result<bool>

Determine whether this expression is nullable, given the schema of the input

fn evaluate(&self, batch: &RecordBatch) -> Result<ColumnarValue>

Evaluate an expression against a RecordBatch

fn return_field(&self, input_schema: &Schema) -> Result<FieldRef>

The output field associated with this expression

fn children(&self) -> Vec<&Arc<dyn PhysicalExpr>>

Get a list of child PhysicalExpr that provide the input for this expr.

fn with_new_children( self: Arc<Self>, children: Vec<Arc<dyn PhysicalExpr>>, ) -> Result<Arc<dyn PhysicalExpr>>

Returns a new PhysicalExpr where all children were replaced by new exprs.

fn evaluate_bounds(&self, children: &[&Interval]) -> Result<Interval>

Computes the output interval for the expression, given the input intervals.

fn propagate_constraints( &self, interval: &Interval, children: &[&Interval], ) -> Result<Option<Vec<Interval>>>

Updates bounds for child expressions, given a known interval for this expression.

fn fmt_sql(&self, f: &mut Formatter<'_>) -> Result

Format this PhysicalExpr in nice human readable “SQL” format

fn try_to_proto( &self, ctx: &PhysicalExprEncodeCtx<'_>, ) -> Result<Option<PhysicalExprNode>>

Available on crate feature proto only.

Serialize this expression to a PhysicalExprNode proto message.

fn evaluate_selection( &self, batch: &RecordBatch, selection: &BooleanArray, ) -> Result<ColumnarValue, DataFusionError>

Evaluate an expression against a RecordBatch after first applying a validity array

fn evaluate_statistics( &self, children: &[&Distribution], ) -> Result<Distribution, DataFusionError>

👎Deprecated since 54.0.0:

Part of the unused Statistics V2 framework; see https://github.com/apache/datafusion/pull/22071

Computes the output statistics for the expression, given the input statistics.

fn propagate_statistics( &self, parent: &Distribution, children: &[&Distribution], ) -> Result<Option<Vec<Distribution>>, DataFusionError>

👎Deprecated since 54.0.0:

Part of the unused Statistics V2 framework; see https://github.com/apache/datafusion/pull/22071

Updates children statistics using the given parent statistic for this expression.

fn snapshot(&self) -> Result<Option<Arc<dyn PhysicalExpr>>, DataFusionError>

Take a snapshot of this PhysicalExpr, if it is dynamic.

fn snapshot_generation(&self) -> u64

Returns the generation of this PhysicalExpr for snapshotting purposes. The generation is an arbitrary u64 that can be used to track changes in the state of the PhysicalExpr over time without having to do an exhaustive comparison. This is useful to avoid unnecessary computation or serialization if there are no changes to the expression. In particular, dynamic expressions that may change over time; this allows cheap checks for changes. Static expressions that do not change over time should return 0, as does the default implementation. You should not call this method directly as it does not handle recursion. Instead use snapshot_generation to handle recursion and capture the full state of the PhysicalExpr.

fn is_volatile_node(&self) -> bool

Returns true if the expression node is volatile, i.e. whether it can return different results when evaluated multiple times with the same input.

fn placement(&self) -> ExpressionPlacement

Returns placement information for this expression.

fn expression_id(&self) -> Option<u64>

Return a stable, globally-unique identifier for this PhysicalExpr, if it has one.