Struct transform::reduction::FoldConstants

pub struct FoldConstants {
    pub limit: Option<usize>,
}

Replace operators on constant collections with constant collections.

Fields

limit: Option<usize>

An optional maximum size, after which optimization can cease.

The None value here indicates no maximum size, but does not currently guarantee that any constant expression will be reduced to a MirRelationExpr::Constant variant.

Implementations

impl FoldConstants

pub fn action(
    &self,
    relation: &mut MirRelationExpr,
    relation_type: &mut RelationType,
    input_types: &[RelationType]
) -> Result<(), TransformError>

Replace operators on constants collections with constant collections.

This transform will cease optimization if it encounters constant collections that are larger than self.limit, if that is set. It is not guaranteed that a constant input within the limit will be reduced to a Constant variant.

fn fold_reduce_constant(
    group_key: &[MirScalarExpr],
    aggregates: &[AggregateExpr],
    rows: &[(Row, Diff)]
) -> Result<Vec<(Row, Diff)>, EvalError>

fn fold_topk_constant<'a>(
    group_key: &[usize],
    order_key: &[ColumnOrder],
    limit: &Option<usize>,
    offset: &usize,
    rows: &'a mut [(Row, Diff)]
)

fn fold_flat_map_constant(
    func: &TableFunc,
    exprs: &[MirScalarExpr],
    rows: &[(Row, Diff)],
    limit: Option<usize>
) -> Result<Option<Vec<(Row, Diff)>>, EvalError>

fn fold_filter_constant(
    predicates: &[MirScalarExpr],
    rows: &[(Row, Diff)]
) -> Result<Vec<(Row, Diff)>, EvalError>

Trait Implementations

impl Debug for FoldConstants

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

Formats the value using the given formatter.

impl Transform for FoldConstants

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

Transform a relation into a functionally equivalent relation.

fn debug(&self) -> String

A string describing the transform.