datafusion_common/
null_equality.rs

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17
18/// Represents the behavior for null values when evaluating equality. Currently, its primary use
19/// case is to define the behavior of joins for null values.
20///
21/// # Examples
22///
23/// The following table shows the expected equality behavior for `NullEquality`.
24///
25/// | A    | B    | NullEqualsNothing | NullEqualsNull |
26/// |------|------|-------------------|----------------|
27/// | NULL | NULL | false             | true           |
28/// | NULL | 'b'  | false             | false          |
29/// | 'a'  | NULL | false             | false          |
30/// | 'a'  | 'b'  | false             | false          |
31///
32/// # Order
33///
34/// The order on this type represents the "restrictiveness" of the behavior. The more restrictive
35/// a behavior is, the fewer elements are considered to be equal to null.
36/// [NullEquality::NullEqualsNothing] represents the most restrictive behavior.
37///
38/// This mirrors the old order with `null_equals_null` booleans, as `false` indicated that
39/// `null != null`.
40#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Hash)]
41pub enum NullEquality {
42    /// Null is *not* equal to anything (`null != null`)
43    NullEqualsNothing,
44    /// Null is equal to null (`null == null`)
45    NullEqualsNull,
46}
datafusion_common/null_equality.rs

datafusion_common/
null_equality.rs
