Struct datafusion_optimizer::replace_distinct_aggregate::ReplaceDistinctWithAggregate

pub struct ReplaceDistinctWithAggregate {}

Optimizer that replaces logical [Distinct] with a logical [Aggregate]

SELECT DISTINCT a, b FROM tab

Into

SELECT a, b FROM tab GROUP BY a, b

On the other hand, for a DISTINCT ON query the replacement is a bit more involved and effectively converts

SELECT DISTINCT ON (a) b FROM tab ORDER BY a DESC, c

into

SELECT b FROM (
    SELECT a, FIRST_VALUE(b ORDER BY a DESC, c) AS b
    FROM tab
    GROUP BY a
)
ORDER BY a DESC

Optimizer that replaces logical [Distinct] with a logical [Aggregate]

Implementations

impl ReplaceDistinctWithAggregate

pub fn new() -> Self

Trait Implementations

impl Default for ReplaceDistinctWithAggregate

fn default() -> ReplaceDistinctWithAggregate

Returns the “default value” for a type.

impl OptimizerRule for ReplaceDistinctWithAggregate

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>>

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

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 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.