Struct StaticProvider 

pub struct StaticProvider { /* private fields */ }

HashMap-backed provider suitable for tests and for callers who gather stats once per plan.

Implementations

impl StaticProvider

pub fn new() -> StaticProvider

Build an empty provider.

pub fn with_table( self, table: impl Into<String>, stats: TableStats, ) -> StaticProvider

Register or replace table-level stats.

pub fn with_index( self, table: impl Into<String>, column: impl Into<String>, stats: IndexStats, ) -> StaticProvider

Register or replace an index on (table, column).

pub fn insert_table(&mut self, table: impl Into<String>, stats: TableStats)

Mutable table insert for iterative builds.

pub fn insert_index( &mut self, table: impl Into<String>, column: impl Into<String>, stats: IndexStats, )

Mutable index insert.

pub fn with_histogram( self, table: impl Into<String>, column: impl Into<String>, histogram: Histogram, ) -> StaticProvider

Register or replace an equi-depth histogram on (table, column).

pub fn with_mcv( self, table: impl Into<String>, column: impl Into<String>, mcv: MostCommonValues, ) -> StaticProvider

Register or replace an MCV list on (table, column).

Trait Implementations

impl Clone for StaticProvider

fn clone(&self) -> StaticProvider

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StaticProvider

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

Formats the value using the given formatter.

impl Default for StaticProvider

fn default() -> StaticProvider

Returns the “default value” for a type.

impl StatsProvider for StaticProvider

fn table_stats(&self, table: &str) -> Option<TableStats>

Return row-count / page-count / column metadata for table, or None when stats are not available.

fn index_stats(&self, table: &str, column: &str) -> Option<IndexStats>

Return the IndexStats backing a secondary index on (table, column), if one exists. The planner uses IndexStats::point_selectivity to derive equality selectivity instead of the 0.01 constant.

fn column_histogram(&self, table: &str, column: &str) -> Option<Histogram>

Optional equi-depth histogram for the column. Defaults to None, in which case the planner falls back to its uniform 0.3 range heuristic.

fn column_mcv(&self, table: &str, column: &str) -> Option<MostCommonValues>

Optional most-common-values list for the column. Defaults to None, in which case the planner falls back to its uniform 0.01 equality heuristic. Use for skewed columns where one or two values dominate the table.

fn column_stats(&self, table: &str, column: &str) -> Option<ColumnStats>

Return per-column statistics (distinct count, null count, min/max) when available. Default implementation derives from StatsProvider::table_stats when present.

fn has_index(&self, table: &str, column: &str) -> bool

Convenience: does a usable index exist on (table, column)?

fn distinct_values(&self, table: &str, column: &str) -> Option<u64>

Convenience: distinct-value count for a column, via column stats or an index on that column, whichever is available.