Struct datafusion_physical_expr::expressions::CaseExpr

pub struct CaseExpr { /* private fields */ }

The CASE expression is similar to a series of nested if/else and there are two forms that can be used. The first form consists of a series of boolean “when” expressions with corresponding “then” expressions, and an optional “else” expression.

CASE WHEN condition THEN result [WHEN …] [ELSE result] END

The second form uses a base expression and then a series of “when” clauses that match on a literal value.

CASE expression WHEN value THEN result [WHEN …] [ELSE result] END

Implementations

impl CaseExpr

pub fn try_new( expr: Option<Arc<dyn PhysicalExpr>>, when_then_expr: Vec<(Arc<dyn PhysicalExpr>, Arc<dyn PhysicalExpr>)>, else_expr: Option<Arc<dyn PhysicalExpr>> ) -> Result<Self>

Create a new CASE WHEN expression

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

Optional base expression that can be compared to literal values in the “when” expressions

pub fn when_then_expr( &self ) -> &[(Arc<dyn PhysicalExpr>, Arc<dyn PhysicalExpr>)]

One or more when/then expressions

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

Optional “else” expression

Trait Implementations

impl Debug for CaseExpr

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

Formats the value using the given formatter.

impl Display for CaseExpr

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

Formats the value using the given formatter.

impl Hash for CaseExpr

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<dyn Any> for CaseExpr

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PhysicalExpr for CaseExpr

fn as_any(&self) -> &dyn Any

Return a reference to Any that can be used for down-casting

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

Get the data type of this expression, given the schema of the input

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 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 dyn_hash(&self, state: &mut dyn Hasher)

Update the hash state with this expression requirements from Hash.

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

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

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

Computes bounds for the expression using interval arithmetic.

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

Updates/shrinks bounds for the expression using interval arithmetic. If constraint propagation reveals an infeasibility, returns None for the child causing infeasibility. If none of the children intervals change, may return an empty vector instead of cloning children.

fn get_ordering(&self, _children: &[SortProperties]) -> SortProperties

The order information of a PhysicalExpr can be estimated from its children. This is especially helpful for projection expressions. If we can ensure that the order of a PhysicalExpr to project matches with the order of SortExec, we can eliminate that SortExecs.