Struct mz_transform::movement::ProjectionPushdown

pub struct ProjectionPushdown {
    recursion_guard: RecursionGuard,
}

Pushes projections down through other operators.

Fields

recursion_guard: RecursionGuard

Implementations

impl ProjectionPushdown

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

Pushes the desired_projection down through relation.

This action transforms relation to a MirRelationExpr equivalent to relation.project(desired_projection).

desired_projection is expected to consist of unique columns.

pub fn update_projection_around_get( &self, relation: &mut MirRelationExpr, applied_projections: &BTreeMap<Id, (Vec<usize>, RelationType)>, )

When we push the desired_value_projection at value, the columns returned by Get(get_id) will change, so we need to permute Projects around Get(get_id).

Trait Implementations

impl CheckedRecursion for ProjectionPushdown

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 ProjectionPushdown

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

Formats the value using the given formatter.

impl Default for ProjectionPushdown

fn default() -> Self

Returns the “default value” for a type.

impl Transform for ProjectionPushdown

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

Transform a relation into a functionally equivalent relation.

fn debug(&self) -> String

A string describing the transform.