Struct datafusion::physical_optimizer::join_selection::JoinSelection

pub struct JoinSelection {}

For hash join with the partition mode PartitionMode::Auto, JoinSelection rule will make a cost based decision to select which PartitionMode mode(Partitioned/CollectLeft) is optimal based on the available statistics that the inputs have. If the statistics information is not available, the partition mode will fall back to PartitionMode::Partitioned.

JoinSelection rule will also reorder the build and probe phase of the hash joins based on the avaliable statistics that the inputs have. The rule optimizes the order such that the left (build) side of the join is the smallest. If the statistics information is not available, the order stays the same as the original query. JoinSelection rule will also swap the left and right sides for cross join to keep the left side is the smallest.

Implementations

impl JoinSelection

pub fn new() -> Self

Trait Implementations

impl Default for JoinSelection

fn default() -> JoinSelection

Returns the “default value” for a type.

impl PhysicalOptimizerRule for JoinSelection

fn optimize( &self, plan: Arc<dyn ExecutionPlan>, config: &ConfigOptions ) -> Result<Arc<dyn ExecutionPlan>>

Rewrite plan to an optimized form

fn name(&self) -> &str

A human readable name for this optimizer rule

fn schema_check(&self) -> bool

A flag to indicate whether the physical planner should valid the rule will not change the schema of the plan after the rewriting. Some of the optimization rules might change the nullable properties of the schema and should disable the schema check.