Struct IndexInfo 

pub struct IndexInfo {
    pub idx_num: i32,
    pub idx_str: Option<String>,
    pub order_by_consumed: bool,
    pub estimated_cost: f64,
    pub estimated_rows: u32,
    pub constraint_usages: Vec<ConstraintUsage>,
}

The internal (core) representation of an ‘index’ on a virtual table. Returned from xBestIndex and then processed and passed to VFilter.

Fields

idx_num: i32

The index number, used to identify the index internally by the VTab

idx_str: Option<String>

Optional index name. these are passed to vfilter in a tuple (idx_num, idx_str)

order_by_consumed: bool

Whether the index is used for order by

estimated_cost: f64

TODO: for eventual cost based query planning

estimated_rows: u32

Estimated number of rows that the query will return

constraint_usages: Vec<ConstraintUsage>

List of constraints that can be used to optimize the query.

Implementations

impl IndexInfo

pub fn to_ffi(self) -> ExtIndexInfo

Converts IndexInfo to an FFI-safe ExtIndexInfo. This method transfers ownership of constraint_usages and idx_str, which must later be reclaimed using from_ffi to prevent leaks.

pub unsafe fn from_ffi(ffi: ExtIndexInfo) -> Self

Reclaims ownership of constraint_usages and idx_str from an FFI-safe ExtIndexInfo.

Safety

This method is unsafe because it can cause memory leaks if not used correctly. to_ffi and from_ffi are meant to send index info across ffi bounds then immediately reclaim it.

Trait Implementations

impl Clone for IndexInfo

fn clone(&self) -> IndexInfo

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IndexInfo

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

Formats the value using the given formatter.

impl Default for IndexInfo

fn default() -> Self

Returns the “default value” for a type.