Struct Schema 

pub struct Schema { /* private fields */ }

One operator’s output columns.

The fields and the bindings are parallel and always the same length, which Schema::new checks. They are two vectors rather than a vector of pairs because a caller almost always wants one of them whole: the result set wants the names and the types, and the expression evaluator wants to search the bindings.

Implementations

impl Schema

pub fn new(fields: Vec<Field>, bindings: Vec<ColumnBinding>) -> Result<Self>

A schema of fields, bound at bindings.

Errors

If the two are not the same length, which would make a binding resolve to the wrong column or to no column at all.

pub fn numbered(fields: Vec<Field>, table: u32) -> Self

A schema of fields numbered from zero against table.

The common case, since an operator that introduces columns numbers them in the order it produces them and the binder does the same.

Panics

If there are more than u32::MAX fields, which is the bound a binding’s position already carries.

pub fn empty() -> Self

A schema with no columns, which is what Node::Dummy produces.

pub fn fields(&self) -> &[Field]

The fields, in output order.

pub fn bindings(&self) -> &[ColumnBinding]

The bindings, in output order.

pub fn width(&self) -> usize

How many columns.

pub fn is_empty(&self) -> bool

Whether there are no columns.

pub fn types(&self) -> Vec<LogicalType>

The column types, in order.

pub fn names(&self) -> Vec<String>

The column names, in order.

pub fn position_of(&self, binding: ColumnBinding) -> Option<usize>

Where a binding sits in the output.

A linear scan. An operator’s schema is as wide as the query is, which is tens of columns on the widest ClickBench query, and a hash map of tens of entries rebuilt per operator costs more than the scans it saves.

pub fn concat(left: &Self, right: &Self) -> Self

The left schema’s columns followed by the right schema’s, which is what a join produces.

Trait Implementations

impl Clone for Schema

fn clone(&self) -> Schema

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Schema

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

Formats the value using the given formatter.

impl Eq for Schema

impl PartialEq for Schema

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Schema