grafeo_engine::query::optimizer::cardinality

Struct SelectivityConfig

pub struct SelectivityConfig {
    pub default: f64,
    pub equality: f64,
    pub inequality: f64,
    pub range: f64,
    pub string_ops: f64,
    pub membership: f64,
    pub is_null: f64,
    pub is_not_null: f64,
    pub distinct_fraction: f64,
}

Expand description

Configurable selectivity defaults for cardinality estimation.

Controls the assumed selectivity for various predicate types when histogram or column statistics are unavailable. Adjusting these values can improve plan quality for workloads with known skew.

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§default: f64

Selectivity for unknown predicates (default: 0.1).

§equality: f64

Selectivity for equality predicates without stats (default: 0.01).

§inequality: f64

Selectivity for inequality predicates (default: 0.99).

§range: f64

Selectivity for range predicates without stats (default: 0.33).

§string_ops: f64

Selectivity for string operations: STARTS WITH, ENDS WITH, CONTAINS, LIKE (default: 0.1).

§membership: f64

Selectivity for IN membership (default: 0.1).

§is_null: f64

Selectivity for IS NULL (default: 0.05).

§is_not_null: f64

Selectivity for IS NOT NULL (default: 0.95).

§distinct_fraction: f64

Fraction assumed distinct for DISTINCT operations (default: 0.5).

Implementations§

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impl SelectivityConfig

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pub fn new() -> Self

Creates a new config with standard database defaults.

Trait Implementations§

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impl Clone for SelectivityConfig

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fn clone(&self) -> SelectivityConfig

Returns a duplicate of the value. Read more

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

Performs copy-assignment from source. Read more

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impl Debug for SelectivityConfig

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

Formats the value using the given formatter. Read more

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impl Default for SelectivityConfig

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fn default() -> Self

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

Auto Trait Implementations§

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impl UnwindSafe for SelectivityConfig

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)

Performs copy-assignment from self to dest. Read more

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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

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

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fn in_current_span(self) -> Instrumented<Self>

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

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impl<T, U> Into for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

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

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more

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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more

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