Struct mz_transform::non_null_requirements::NonNullRequirements

pub struct NonNullRequirements {
    recursion_guard: RecursionGuard,
}

Push non-null requirements toward sources.

Fields

recursion_guard: RecursionGuard

Implementations

impl NonNullRequirements

pub fn action( &self, relation: &mut MirRelationExpr, columns: BTreeSet<usize>, gets: &mut BTreeMap<Id, Vec<BTreeSet<usize>>>, ) -> Result<(), TransformError>

Push non-null requirements toward sources.

The action computes and pushes columns in a top-down manner and simplifies the associated tree. The columns value denotes a set of output columns that entail the associated relation will evaluate to the constant empty collection if any column is null. This information is used to simplify and prune sub-trees in the Constant and Map cases.

Trait Implementations

impl CheckedRecursion for NonNullRequirements

fn recursion_guard(&self) -> &RecursionGuard

Extracts a reference to the recursion guard embedded within the type.

fn checked_recur<F, T, E>(&self, f: F) -> Result<T, E>

where F: FnOnce(&Self) -> Result<T, E>, E: From<RecursionLimitError>,

Checks whether it is safe to recur and calls f if so.

fn checked_recur_mut<F, T, E>(&mut self, f: F) -> Result<T, E>

where F: FnOnce(&mut Self) -> Result<T, E>, E: From<RecursionLimitError>,

Like CheckedRecursion::checked_recur, but operates on a mutable reference to Self.

impl Debug for NonNullRequirements

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

Formats the value using the given formatter.

impl Default for NonNullRequirements

fn default() -> NonNullRequirements

Returns the “default value” for a type.

impl Transform for NonNullRequirements

fn name(&self) -> &'static str

A short string naming the transform, as it will be reported in metrics.

fn actually_perform_transform( &self, relation: &mut MirRelationExpr, _: &mut TransformCtx<'_>, ) -> Result<(), TransformError>

Transform a relation into a functionally equivalent relation.

fn transform( &self, relation: &mut MirRelationExpr, args: &mut TransformCtx<'_>, ) -> Result<(), TransformError>

Transforms a relation into a functionally equivalent relation.

fn debug(&self) -> String

A string describing the transform.