Enum Relate 

pub enum Relate {
    Recognise,
    Refuse,
}

Whether the decomposition may read a loop as a join.

The off switch docs/08 §8.3 item 8 requires of anything the compiler decides for you — “a default nobody has run is a claim, so the switched-off path belongs in a gate beside the fast one”. Recognising a join (crate::relate) changes which operators a program compiles to without the program saying so, which is exactly the kind of choice that item is about, and scaling.rs::maintaining_a_view_whose_loop_looks_something_up_costs_the_same_at_any_size measures both settings so the gate carries its own evidence that it can fail.

It is a compile-time switch rather than an AppConfig field because a plan is compiled once, before a runtime exists: beck explain query --no-join and beck explain cost --no-join are where a developer reaches it.

Variants

Recognise

Read for x in xs: whose body looks something up as an equi-join (docs/99 §99.6).

Refuse

Leave every loop as the captured map_list its source spells, index nothing, and pay the nested loop per event.

Trait Implementations

impl Clone for Relate

fn clone(&self) -> Relate

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Relate

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

Formats the value using the given formatter.

impl Default for Relate

fn default() -> Relate

Returns the “default value” for a type.

impl PartialEq for Relate

fn eq(&self, other: &Relate) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Relate

impl Eq for Relate

impl StructuralPartialEq for Relate