pub struct Demand {
    recursion_guard: RecursionGuard,
}
Expand description

Drive demand from the root through operators.

This transform alerts operators to their columns that influence the ultimate output of the expression, and gives them permission to swap other columns for dummy values. As part of this, operators should not actually use any of these dummy values, lest they run-time error.

This transformation primarily informs the Join operator, which can simplify its intermediate state when it knows that certain columns are not observed in its output. Internal arrangements need not maintain columns that are no longer required in the join pipeline, which are those columns not required by the output nor any further equalities.

Fields

recursion_guard: RecursionGuard

Implementations

Columns to be produced.

Trait Implementations

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

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

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

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Transform a relation into a functionally equivalent relation.

A string describing the transform. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Attaches the provided Context to this type, returning a WithContext wrapper. Read more

Attaches the current Context to this type, returning a WithContext wrapper. Read more

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Wrap the input message T in a tonic::Request

The alignment of pointer.

The type for initializers.

Initializes a with the given initializer. Read more

Dereferences the given pointer. Read more

Mutably dereferences the given pointer. Read more

Drops the object pointed to by the given pointer. Read more

Should always be Self

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more