datafusion_physical_optimizer/
optimizer.rs

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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Physical optimizer traits

use datafusion_common::config::ConfigOptions;
use datafusion_common::Result;
use datafusion_physical_plan::ExecutionPlan;
use std::fmt::Debug;
use std::sync::Arc;

/// `PhysicalOptimizerRule` transforms one ['ExecutionPlan'] into another which
/// computes the same results, but in a potentially more efficient way.
///
/// Use [`SessionState::add_physical_optimizer_rule`] to register additional
/// `PhysicalOptimizerRule`s.
///
/// [`SessionState::add_physical_optimizer_rule`]: https://docs.rs/datafusion/latest/datafusion/execution/session_state/struct.SessionState.html#method.add_physical_optimizer_rule
pub trait PhysicalOptimizerRule: Debug {
    /// Rewrite `plan` to an optimized form
    fn optimize(
        &self,
        plan: Arc<dyn ExecutionPlan>,
        config: &ConfigOptions,
    ) -> Result<Arc<dyn ExecutionPlan>>;

    /// A human readable name for this optimizer rule
    fn name(&self) -> &str;

    /// 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.
    fn schema_check(&self) -> bool;
}