io.trino.sql.planner.iterative.Memo

public class Memo extends Object

Stores a plan in a form that's efficient to mutate locally (i.e. without having to do full ancestor tree rewrites due to plan nodes being immutable).

Each node in a plan is placed in a group, and it's children are replaced with symbolic references to the corresponding groups.

For example, a plan like:

    A -> B -> C -> D
           \> E -> F

would be stored as:

 root: G0

 G0 : { A -> G1 }
 G1 : { B -> [G2, G3] }
 G2 : { C -> G4 }
 G3 : { E -> G5 }
 G4 : { D }
 G5 : { F }

Groups are reference-counted, and groups that become unreachable from the root due to mutations in a subtree get garbage-collected.

Constructor Details
- Memo
  
  public Memo(PlanNodeIdAllocator idAllocator, PlanNode plan)
Method Details
- getRootGroup
  
  public int getRootGroup()
- getNode
  
  public PlanNode getNode(int group)
- resolve
  
  public PlanNode resolve(GroupReference groupReference)
- extract
  
  public PlanNode extract()
- replace
  
  public PlanNode replace(int groupId, PlanNode node, String reason)
- getStats
  
  public Optional<PlanNodeStatsEstimate> getStats(int group)
- storeStats
  
  public void storeStats(int groupId, PlanNodeStatsEstimate stats)
- getCost
  
  public Optional<PlanCostEstimate> getCost(int group)
- storeCost
  
  public void storeCost(int group, PlanCostEstimate cost)
- getGroupCount
  
  public int getGroupCount()

Class Memo

Constructor Summary