Enum Rule 

pub enum Rule {
    StatsAll,
    Presize,
    DirectAddressing,
    ValidityFree,
    FilterOrder,
    TopNSeed,
    NarrowArithmetic,
    JoinElimination,
    MemoryReservation,
    GraphSections,
}

One switch.

Every statistics variant is on by default, so a fresh database behaves as it did before any of this existed and an ablation is something a run asks for rather than something it inherits. Rule::GraphSections is the exception and starts off, because it is a stored structure and a new path through the executor rather than a better answer to a question already being asked.

Variants

StatsAll

Every statistics consumer. Off means every question answers Stat::Unknown.

Presize

Presizing a hash aggregate from the distinct count of its grouping key.

DirectAddressing

Choosing direct addressing over hashing when the key range is small and dense.

ValidityFree

Dropping the validity handling in a kernel whose input has an exact zero null count.

FilterOrder

Ordering the conjuncts of a filter by selectivity over evaluation cost.

TopNSeed

Seeding a top-n threshold from a certified quantile instead of from infinity.

NarrowArithmetic

Summing a decimal column in i64 when its exact bounds fit, rather than in i128.

JoinElimination

Removing a join whose relationship is verified and whose columns nothing above it reads.

MemoryReservation

Reserving memory for an operator from what its input statistics say it will need.

GraphSections

Every stored graph section. Off means the sections are not read and no plan uses one.

Implementations

impl Rule

pub const ALL: [Self; 10]

Every rule, in the order a report lists them.

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

The canonical name, which is what a setting reads back as.

pub const fn master(self) -> Option<Self>

The rule that turns this one off from above, if there is one.

A per rule switch is not enough on its own: the ablation of section 9.3 is one statement and it has to reach every consumer, including the ones added after it was written.

pub const fn starts_on(self) -> bool

Whether a fresh database has this rule on.

Everything does except Rule::GraphSections, and the reason is in the module docs.

pub fn from_name(key: &str) -> Option<Self>

The rule a settings key names, in any of its spellings.

Trait Implementations

impl Clone for Rule

fn clone(&self) -> Rule

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Rule

impl Debug for Rule

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

Formats the value using the given formatter.

impl Eq for Rule

impl Hash for Rule

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Rule

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Rule