Trait datafusion_optimizer::expr_simplifier::ExprSimplifiable

pub trait ExprSimplifiable: Sized {
    fn simplify<S: SimplifyInfo>(self, info: &S) -> Result<Self>;
}

trait for types that can be simplified

Required Methods

fn simplify<S: SimplifyInfo>(self, info: &S) -> Result<Self>

simplify this trait object using the given SimplifyInfo

Implementations on Foreign Types

impl ExprSimplifiable for Expr

fn simplify<S: SimplifyInfo>(self, info: &S) -> Result<Self>

Simplifies this Expr`s as much as possible, evaluating constants and applying algebraic simplifications

Example:

b > 2 AND b > 2 can be written to b > 2

use datafusion_expr::{col, lit, Expr};
use datafusion_common::Result;
use datafusion_physical_expr::execution_props::ExecutionProps;
use datafusion_optimizer::expr_simplifier::{SimplifyInfo, ExprSimplifiable};

/// Simple implementation that provides `Simplifier` the information it needs
#[derive(Default)]
struct Info {
  execution_props: ExecutionProps,
};

impl SimplifyInfo for Info {
  fn is_boolean_type(&self, expr: &Expr) -> Result<bool> {
    Ok(false)
  }
  fn nullable(&self, expr: &Expr) -> Result<bool> {
    Ok(true)
  }
  fn execution_props(&self) -> &ExecutionProps {
    &self.execution_props
  }
}

// b < 2
let b_lt_2 = col("b").gt(lit(2));

// (b < 2) OR (b < 2)
let expr = b_lt_2.clone().or(b_lt_2.clone());

// (b < 2) OR (b < 2) --> (b < 2)
let expr = expr.simplify(&Info::default()).unwrap();
assert_eq!(expr, b_lt_2);

Implementors