Trait deltalake::datafusion::optimizer::optimizer::OptimizerRule

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pub trait OptimizerRule {
    // Required methods
    fn try_optimize(
        &self,
        plan: &LogicalPlan,
        config: &dyn OptimizerConfig
    ) -> Result<Option<LogicalPlan>, DataFusionError>;
    fn name(&self) -> &str;

    // Provided method
    fn apply_order(&self) -> Option<ApplyOrder> { ... }
}

Expand description

OptimizerRule transforms one LogicalPlan into another which computes the same results, but in a potentially more efficient way. If there are no suitable transformations for the input plan, the optimizer should simply return it unmodified.

To change the semantics of a LogicalPlan, see AnalyzerRule

Use SessionState::add_optimizer_rule to register additional OptimizerRules.

Required Methods§

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

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

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fn name(&self) -> &str

A human readable name for this optimizer rule

Provided Methods§

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

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

If a rule use default None, it should traverse recursively plan inside itself

Implementors§

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impl OptimizerRule for CommonSubexprEliminate

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impl OptimizerRule for DecorrelatePredicateSubquery

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impl OptimizerRule for EliminateCrossJoin

Attempt to reorder join to eliminate cross joins to inner joins. for queries: ‘select … from a, b where a.x = b.y and b.xx = 100;’ ‘select … from a, b where (a.x = b.y and b.xx = 100) or (a.x = b.y and b.xx = 200);’ ‘select … from a, b, c where (a.x = b.y and b.xx = 100 and a.z = c.z) or (a.x = b.y and b.xx = 200 and a.z=c.z);’ ‘select … from a, b where a.x > b.y’ For above queries, the join predicate is available in filters and they are moved to join nodes appropriately This fix helps to improve the performance of TPCH Q19. issue#78

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