Struct TryCastExpr 

pub struct TryCastExpr { /* private fields */ }

TRY_CAST expression casts an expression to a specific data type and returns NULL on invalid cast

Implementations

impl TryCastExpr

pub fn new(expr: Arc<dyn PhysicalExpr>, cast_type: DataType) -> Self

Create a new TryCastExpr using only a DataType.

This constructor creates a type-only cast where metadata is passed through from the source expression (with extension type keys stripped). TRY_CAST results are always nullable since failed casts return NULL.

pub fn new_with_target_field( expr: Arc<dyn PhysicalExpr>, target_field: FieldRef, ) -> Self

Create a new TryCastExpr 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

TRY_CAST results are always nullable since failed casts return NULL.

See TryCastExpr::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_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. TRY_CAST results are always nullable regardless of the target field’s nullability.

impl TryCastExpr

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

Available on crate feature proto only.

Reconstruct a TryCastExpr from its protobuf representation.

Trait Implementations

impl Clone for TryCastExpr

fn clone(&self) -> TryCastExpr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TryCastExpr

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

Formats the value using the given formatter.

impl Display for TryCastExpr

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

Formats the value using the given formatter.

impl Eq for TryCastExpr

impl Hash for TryCastExpr

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 TryCastExpr

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

Equality operator ==.

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

Inequality operator !=.

impl PhysicalExpr for TryCastExpr

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 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_bounds( &self, _children: &[&Interval], ) -> Result<Interval, DataFusionError>

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

fn propagate_constraints( &self, _interval: &Interval, _children: &[&Interval], ) -> Result<Option<Vec<Interval>>, DataFusionError>

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

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 get_properties( &self, _children: &[ExprProperties], ) -> Result<ExprProperties, DataFusionError>

Calculates the properties of this PhysicalExpr based on its children’s properties (i.e. order and range), recursively aggregating the information from its children. In cases where the PhysicalExpr has no children (e.g., Literal or Column), these properties should be specified externally, as the function defaults to unknown properties.

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.