Enum TextCast 

pub enum TextCast {
    Direct(&'static str),
    ClickHouseNullTolerant(&'static str),
}

How a dialect casts one call-site argument to text.

The hash is a hash of a string and a call-site argument is a raw column of its own declared type, so the cast is not optional.

Variants

Direct(&'static str)

CAST(x AS <type>) — the cast propagates NULL, so Razeri’s NULL sentinel is reached with the statement intact.

ClickHouseNullTolerant(&'static str)

assumeNotNull(CAST(x AS Nullable(<type>))) — ClickHouse, whose CAST to a non-Nullable type raises instead of propagating (“Cannot convert NULL to a non-nullable type”).

ClickHouse evaluates both arms of a CASE, so the sentinel cannot save the statement: the emitted key expression failed outright on any NULL natural-key part rather than returning the sentinel. That is not a wrong key — it is a dimension load that does not run. The wrapper makes the unreachable arm total; which value it would produce is irrelevant, because the sentinel has already answered.

Trait Implementations

impl Clone for TextCast

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for TextCast

impl Debug for TextCast

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

Formats the value using the given formatter.

impl Eq for TextCast

impl PartialEq for TextCast

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for TextCast