Enum EmptyRead 

pub enum EmptyRead {
    Refuse,
    Allow,
}

What an Arrow read of ZERO rows means.

It is a policy, not a detail, because the two readings are opposite and both look identical on the wire:

• “the table really is empty” — a legitimate Ok, nothing to build;
• “I asked for a full build of orders and the catalog handed me nothing” — a mis-pointed warehouse, a wrong namespace, an unrefreshed snapshot. Shipping that as a successful round writes an EMPTY GRAPH that looks exactly like a built one, and nobody finds out until someone opens the viewer.

The default is EmptyRead::Refuse, because the second reading is the common one and the first is easy to declare.

Variants

Refuse

A zero-row read is a typed BifrostError::Source naming the table and the producer. The default.

Allow

A zero-row read is Ok(None) — the caller has said this table may legitimately be empty.

Trait Implementations

impl Clone for EmptyRead

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 EmptyRead

impl Debug for EmptyRead

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

Formats the value using the given formatter.

impl Default for EmptyRead

fn default() -> Self

Returns the “default value” for a type.

impl Eq for EmptyRead

impl PartialEq for EmptyRead

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for EmptyRead