Struct datafusion_optimizer::simplify_expressions::GuaranteeRewriter

pub struct GuaranteeRewriter<'a> { /* private fields */ }

Rewrite expressions to incorporate guarantees.

Guarantees are a mapping from an expression (which currently is always a column reference) to a NullableInterval. The interval represents the known possible values of the column. Using these known values, expressions are rewritten so they can be simplified using ConstEvaluator and Simplifier.

For example, if we know that a column is not null and has values in the range [1, 10), we can rewrite x IS NULL to false or x < 10 to true.

See a full example in ExprSimplifier::with_guarantees().

Implementations

impl<'a> GuaranteeRewriter<'a>

pub fn new( guarantees: impl IntoIterator<Item = &'a (Expr, NullableInterval)>, ) -> Self

Trait Implementations

impl<'a> TreeNodeRewriter for GuaranteeRewriter<'a>

type Node = Expr

The node type which is rewritable.

fn f_up(&mut self, expr: Expr) -> Result<Transformed<Expr>>

Invoked while traversing up the tree after all children have been rewritten. Default implementation returns the node as is and continues recursion.

fn f_down( &mut self, node: Self::Node, ) -> Result<Transformed<Self::Node>, DataFusionError>

Invoked while traversing down the tree before any children are rewritten. Default implementation returns the node as is and continues recursion.