Struct datafusion_optimizer::extract_equijoin_predicate::ExtractEquijoinPredicate

pub struct ExtractEquijoinPredicate;

Optimizer that splits conjunctive join predicates into equijoin predicates and (other) filter predicates.

Join algorithms are often highly optimized for equality predicates such as x = y, often called equijoin predicates, so it is important to locate such predicates and treat them specially.

For example, SELECT ... FROM A JOIN B ON (A.x = B.y AND B.z > 50) has one equijoin predicate (A.x = B.y) and one filter predicate (B.z > 50). See find_valid_equijoin_key_pair for more information on what predicates are considered equijoins.

Implementations

impl ExtractEquijoinPredicate

pub fn new() -> Self

Trait Implementations

impl Default for ExtractEquijoinPredicate

fn default() -> ExtractEquijoinPredicate

Returns the “default value” for a type.

impl OptimizerRule for ExtractEquijoinPredicate

fn try_optimize( &self, plan: &LogicalPlan, _config: &dyn OptimizerConfig ) -> Result<Option<LogicalPlan>>

Try and rewrite plan to an optimized form, returning None if the plan cannot be optimized by this rule.

fn name(&self) -> &str

A human readable name for this optimizer rule

fn apply_order(&self) -> Option<ApplyOrder>

How should the rule be applied by the optimizer? See comments on ApplyOrder for details.