Struct datafusion::physical_expr::ConstExpr

pub struct ConstExpr { /* private fields */ }

A structure representing a expression known to be constant in a physical execution plan.

The ConstExpr struct encapsulates an expression that is constant during the execution of a query. For example if a predicate like A = 5 applied earlier in the plan A would be known constant

Fields

• expr: Constant expression for a node in the physical plan.

• across_partitions: A boolean flag indicating whether the constant expression is valid across partitions. If set to true, the constant expression has same value for all partitions. If set to false, the constant expression may have different values for different partitions.

Example

let col = lit(5);
// Create a constant expression from a physical expression ref
let const_expr = ConstExpr::from(&col);
// create a constant expression from a physical expression
let const_expr = ConstExpr::from(col);

Implementations

impl ConstExpr

pub fn new(expr: Arc<dyn PhysicalExpr>) -> ConstExpr

Create a new constant expression from a physical expression.

Note you can also use ConstExpr::from to create a constant expression from a reference as well

pub fn with_across_partitions(self, across_partitions: bool) -> ConstExpr

pub fn across_partitions(&self) -> bool

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

pub fn owned_expr(self) -> Arc<dyn PhysicalExpr>

pub fn map<F>(&self, f: F) -> Option<ConstExpr>

where F: Fn(&Arc<dyn PhysicalExpr>) -> Option<Arc<dyn PhysicalExpr>>,

Trait Implementations

impl Clone for ConstExpr

fn clone(&self) -> ConstExpr

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ConstExpr

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

Formats the value using the given formatter.

impl From<&Arc<dyn PhysicalExpr>> for ConstExpr

fn from(expr: &Arc<dyn PhysicalExpr>) -> ConstExpr

Converts to this type from the input type.

impl From<Arc<dyn PhysicalExpr>> for ConstExpr

fn from(expr: Arc<dyn PhysicalExpr>) -> ConstExpr

Converts to this type from the input type.