Struct IndexSelectionRule

pub struct IndexSelectionRule {}

Implementations

impl IndexSelectionRule

fn gen_index_lookup( &self, logical_scan: &LogicalScan, index: &IndexCatalog, ) -> (PlanRef, IndexCost)

fn index_merge_selection( &self, logical_scan: &LogicalScan, ) -> Option<(PlanRef, IndexCost)>

Index Merge Selection Deal with predicate like a = 1 or b = 1 Merge index scans from a table, currently merge is union semantic.

fn gen_paths( &self, conjunctions: &[ExprImpl], logical_scan: &LogicalScan, primary_table_row_size: usize, ) -> Vec<PlanRef>

Generate possible paths that can be used to access. The schema of output is the order key of primary table, so it can be used to lookup primary table later. Method gen_paths handles the complex condition recursively which may contains nested AND and OR. However, Method gen_index_path handles one arm of an OR clause which is a basic unit for index selection.

fn clustering_disjunction( &self, disjunctions: Vec<ExprImpl>, ) -> (HashMap<usize, ExprImpl>, Vec<ExprImpl>)

Clustering disjunction or expr by column index. If expr is complex, classify them as others.

a = 1, b = 2, b = 3 -> map: [a, (a = 1)], [b, (b = 2 or b = 3)], others: []

a = 1, (b = 2 and c = 3) -> map: [a, (a = 1)], others:

(a > 1 and a < 8) or (c > 1 and c < 8) -> map: [], others: [(a > 1 and a < 8), (c > 1 and c < 8)]

fn gen_index_path( &self, column_index: Option<usize>, conjunctions: &[ExprImpl], logical_scan: &LogicalScan, ) -> Vec<PlanRef>

Given a conjunctions from one arm of an OR clause (basic unit to index selection), generate all matching index path (including primary index) for the relation. column_index (refers to primary table) is a hint can be used to prune index. Steps:

1. Take the combination of conjunctions to extract the potential clauses.
2. For each potential clauses, generate index path if it can.

fn build_index_access( &self, index: Rc<IndexCatalog>, predicate: Condition, ctx: OptimizerContextRef, as_of: Option<AsOf>, ) -> Option<PlanRef>

build index access if predicate (refers to primary table) is covered by index

fn merge(&self, paths: Vec<PlanRef>) -> Option<PlanRef>

fn choose_min_cost_path( &self, paths: &[PlanRef], primary_table_row_size: usize, ) -> Option<(PlanRef, IndexCost)>

fn estimate_table_scan_cost( &self, scan: &LogicalScan, row_size: usize, ) -> IndexCost

fn estimate_full_table_scan_cost( &self, scan: &LogicalScan, row_size: usize, ) -> IndexCost

fn create_null_safe_equal_expr( left: usize, left_data_type: DataType, right: usize, right_data_type: DataType, ) -> ExprImpl

impl IndexSelectionRule

pub fn create() -> Box<dyn FallibleRule>

Trait Implementations

impl Description for IndexSelectionRule

fn description(&self) -> &str

impl InfallibleRule for IndexSelectionRule

fn apply(&self, plan: PlanRef) -> Option<PlanRef>

Apply the rule to the plan node.