Enum sqlite3_ext::vtab::DistinctMode

pub enum DistinctMode {
    Ordered,
    Grouped,
    Distinct,
}

Describes the requirements of the virtual table query.

This value is retured by IndexInfo::distinct_mode. It allows the virtual table implementation to decide if it is safe to consume the order_by fields using IndexInfo::set_order_by_consumed.

The levels described here are progressively less demanding. If the virtual table implementation meets the requirements of DistinctMode::Ordered, then it is always safe to consume the order_by fields.

For the purposes of comparing virtual table output values to see if the values are same value for sorting purposes, two NULL values are considered to be the same. In other words, the comparison operator is “IS” (or “IS NOT DISTINCT FROM”) and not “==”.

Variants

Ordered

The virtual table must return all rows in the correct order according to the order_by fields.

Grouped

The virtual table may return rows in any order, but all rows that are in the same group must be adjacent to one another. A group is defined as all rows for which all of the columns in order_by are equal. This is the mode used when planning a GROUP BY query.

Distinct

The same as DistinctMode::Grouped, however the virtual table is allowed (but not required) to skip all but a single row within each group. This is the mode used when planning a DISTINCT query.

Trait Implementations

impl Clone for DistinctMode

fn clone(&self) -> DistinctMode

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DistinctMode

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

Formats the value using the given formatter.

impl PartialEq<DistinctMode> for DistinctMode

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for DistinctMode

impl Eq for DistinctMode

impl StructuralEq for DistinctMode

impl StructuralPartialEq for DistinctMode