Struct SingleDistinctToGroupBy

pub struct SingleDistinctToGroupBy {}

single distinct to group by optimizer rule

  Before:
  SELECT a, count(DISTINCT b), sum(c)
  FROM t
  GROUP BY a

  After:
  SELECT a, count(alias1), sum(alias2)
  FROM (
    SELECT a, b as alias1, sum(c) as alias2
    FROM t
    GROUP BY a, b
  )
  GROUP BY a

Implementations

impl SingleDistinctToGroupBy

pub fn new() -> Self

Trait Implementations

impl Debug for SingleDistinctToGroupBy

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

Formats the value using the given formatter.

impl Default for SingleDistinctToGroupBy

fn default() -> SingleDistinctToGroupBy

Returns the “default value” for a type.

impl OptimizerRule for SingleDistinctToGroupBy

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.

fn supports_rewrite(&self) -> bool

Does this rule support rewriting owned plans (rather than by reference)?

fn rewrite( &self, plan: LogicalPlan, _config: &dyn OptimizerConfig, ) -> Result<Transformed<LogicalPlan>, DataFusionError>

Try to rewrite plan to an optimized form, returning Transformed::yes if the plan was rewritten and Transformed::no if it was not.

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

👎Deprecated since 40.0.0: please implement supports_rewrite and rewrite instead

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