github.com/vescale/zgraph@v0.0.0-20230410094002-959c02d50f95/planner/optimizer.go (about)

     1  // Copyright 2022 zGraph Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package planner
    16  
    17  // Optimize optimizes the plan to the optimal physical plan.
    18  func Optimize(plan LogicalPlan) Plan {
    19  	switch p := plan.(type) {
    20  	case *LogicalMatch:
    21  		return optimizeMatch(p)
    22  	case *LogicalProjection:
    23  		return optimizeProjection(p)
    24  	case *LogicalSelection:
    25  		return optimizeSelection(p)
    26  	}
    27  	return plan
    28  }
    29  
    30  func optimizeMatch(plan *LogicalMatch) Plan {
    31  	result := &PhysicalMatch{}
    32  	result.SetColumns(plan.Columns())
    33  	result.Subgraph = plan.Subgraph
    34  	return result
    35  }
    36  
    37  func optimizeProjection(plan *LogicalProjection) Plan {
    38  	result := &PhysicalProjection{}
    39  	result.SetColumns(plan.Columns())
    40  	result.Exprs = plan.Exprs
    41  	childPlan := Optimize(plan.Children()[0])
    42  	result.SetChildren(childPlan.(PhysicalPlan))
    43  	return result
    44  }
    45  
    46  func optimizeSelection(plan *LogicalSelection) Plan {
    47  	result := &PhysicalSelection{}
    48  	result.SetColumns(plan.Columns())
    49  	result.Condition = plan.Condition
    50  	childPlan := Optimize(plan.Children()[0])
    51  	result.SetChildren(childPlan.(PhysicalPlan))
    52  	return result
    53  }