Struct SortKeySpec 

pub struct SortKeySpec {
    pub expr: SqlExpr,
    pub ascending: bool,
    pub nulls_first: bool,
}

A single ORDER BY term.

The key is an expression, not a column name. ORDER BY 100 / weight, ORDER BY UPPER(name), and ORDER BY qty * price all sort by a value that exists nowhere in the stored row, so a key that could only name a column would have to drop them — answering a query that declared a sort with rows in storage order, and reporting success while doing it.

A bare ORDER BY col is simply the SqlExpr::Column case and still resolves by direct field lookup.

Fields

expr: SqlExpr

Expression evaluated against each row to produce its sort value.

ascending: bool

true = ascending, false = descending.

nulls_first: bool

Where NULLs go: true places them before all non-NULL values, false after.

This is independent of ascending — SQL’s NULLS FIRST / NULLS LAST is absolute and is not flipped by the sort direction. When the query does not say, the planner fills in PostgreSQL’s default (ASC → NULLS LAST, DESC → NULLS FIRST).

Implementations

impl SortKeySpec

pub fn column(name: impl Into<String>, ascending: bool) -> Self

Sort by a bare column name, with PostgreSQL’s default NULL placement for the given direction.

pub fn order_nulls(&self, a_is_null: bool, b_is_null: bool) -> Option<Ordering>

Order two rows that may be NULL on this key.

Some(ordering) when at least one side is NULL — decided entirely by nulls_first, never reversed by the direction. None when both sides carry a value and the caller must compare them.

pub fn direct(&self, ordering: Ordering) -> Ordering

Apply the sort direction to a comparison of two non-NULL values.

pub fn as_column(&self) -> Option<&str>

The column this key sorts by, when the key is a bare column reference.

Storage layers that can only push a stored column down to an index use this to decide whether the key is pushable; a computed key returns None and must be sorted after the rows are materialized.

Trait Implementations

impl Clone for SortKeySpec

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SortKeySpec

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SortKeySpec

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'__msgpack_de> FromMessagePack<'__msgpack_de> for SortKeySpec

fn read<R: Read<'__msgpack_de>>(reader: &mut R) -> Result<Self, Error>

where Self: Sized,

Reads the MessagePack representation of this value from the provided reader.

impl PartialEq for SortKeySpec

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for SortKeySpec

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for SortKeySpec

impl ToMessagePack for SortKeySpec

fn write<W: Write>(&self, writer: &mut W) -> Result<(), Error>

Writes the MessagePack representation of this value into the provided writer.

fn size_hint(&self) -> Option<TrustedSizeHint>

Returns a trusted upper bound for the number of bytes written by the next call to Self::write, or None when it cannot be determined cheaply.

fn max_size() -> Option<TrustedSizeHint>

Returns a trusted upper bound valid for every value of this type.

fn write_slice<W>(values: &[Self], writer: &mut W) -> Result<(), Error>

where W: Write, Self: Sized,

Writes the MessagePack representation of a slice of values into the provided writer.