Struct datafusion_optimizer::optimize_projections::OptimizeProjections

pub struct OptimizeProjections {}

Optimizer rule to prune unnecessary columns from intermediate schemas inside the LogicalPlan. This rule:

• Removes unnecessary columns that do not appear at the output and/or are not used during any computation step.
• Adds projections to decrease table column size before operators that benefit from a smaller memory footprint at its input.
• Removes unnecessary LogicalPlan::Projections from the LogicalPlan.

OptimizeProjections is an optimizer rule that identifies and eliminates columns from a logical plan that are not used by downstream operations. This can improve query performance and reduce unnecessary data processing.

The rule analyzes the input logical plan, determines the necessary column indices, and then removes any unnecessary columns. It also removes any unnecessary projections from the plan tree.

Implementations

impl OptimizeProjections

pub fn new() -> Self

Trait Implementations

impl Default for OptimizeProjections

fn default() -> OptimizeProjections

Returns the “default value” for a type.

impl OptimizerRule for OptimizeProjections

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>>

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.