Enum IndexUsability 

pub enum IndexUsability {
    Equality,
    MultiColumnEquality {
        eq_columns: usize,
        trailing_constraint: MultiColumnTrailingConstraint,
    },
    Range {
        selectivity: f64,
    },
    InExpansion {
        probe_count: usize,
    },
    LikePrefix {
        low: String,
        high: Option<String>,
    },
    NotUsable,
}

Result of analyzing a WHERE term against an index.

Variants

Equality

Index can satisfy an equality constraint on its leftmost column.

MultiColumnEquality

Multi-column equality prefix: equality on the first eq_columns index columns, optionally followed by an additional constraint on the next column.

Fields

eq_columns: usize

Number of leading columns with equality constraints.

trailing_constraint: MultiColumnTrailingConstraint

Constraint on the column immediately after the equality prefix.

Range

Index can satisfy a range constraint (rightmost usable position).

Fields

selectivity: f64

InExpansion

IN (...) expanded to multiple equality probes.

Fields

probe_count: usize

LikePrefix

LIKE/GLOB with a constant prefix and derived upper bound. Represents the range: column >= low and optionally column < high.

Fields

low: String

high: Option<String>

NotUsable

The term cannot use this index.

Trait Implementations

impl Clone for IndexUsability

fn clone(&self) -> IndexUsability

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IndexUsability

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

Formats the value using the given formatter.

impl PartialEq for IndexUsability

fn eq(&self, other: &IndexUsability) -> 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 StructuralPartialEq for IndexUsability