Struct IndexColumnInfo 

pub struct IndexColumnInfo {
    pub column: Option<u16>,
    pub expr_sql: Option<Vec<u8>>,
    pub collation: Vec<u8>,
    pub descending: bool,
    pub declared_descending: bool,
}

One key column of an index.

Fields

column: Option<u16>

The table column this key indexes, when it indexes a bare column.

expr_sql: Option<Vec<u8>>

The key expression, as written, when the key is an expression.

collation: Vec<u8>

The folded collation name the key is ordered by.

descending: bool

Whether the key is stored descending.

declared_descending: bool

Whether the declaration said descending, whatever the storage does.

A different question from descending, and the two used to be one. This engine’s trees are always built ascending, so the catalog flattens descending to false for the planner’s sake - a planner told about a descending tree that does not exist draws three inverted conclusions (see inillucent-catalog’s stored_ascending). But PRAGMA index_xinfo reports what was declared, and an application reading it to reconstruct a CREATE INDEX needs the DESC back.

Implementations

impl IndexColumnInfo

pub fn plain_column(&self) -> Option<u16>

Returns the table column the key holds as it is stored, when it holds one.

Not the same as column. A key on a VIRTUAL generated column names that column, so PRAGMA index_info, a unique violation’s message and DROP COLUMN all see it, and it also carries the column’s expression in expr_sql, because the column is in no record and every entry has to be computed. The binder replaces a reference to such a column with its expression, so a planner that matched the key by column would never find a term to seek on. The planner reads this instead and matches a computed key by its expression.

Trait Implementations

impl Clone for IndexColumnInfo

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 IndexColumnInfo

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

Formats the value using the given formatter.

impl Eq for IndexColumnInfo

impl PartialEq for IndexColumnInfo

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for IndexColumnInfo