io.prestosql.sql.planner.iterative

Class Memo

java.lang.Object

io.prestosql.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 Summary

Constructors

Constructor and Description
Memo(PlanNodeIdAllocator idAllocator, PlanNode plan)

Method Summary

Modifier and Type	Method and Description
PlanNode	extract()
Optional<PlanCostEstimate>	getCost(int group)
int	getGroupCount()
PlanNode	getNode(int group)
int	getRootGroup()
Optional<PlanNodeStatsEstimate>	getStats(int group)
PlanNode	replace(int group, PlanNode node, String reason)
PlanNode	resolve(GroupReference groupReference)
void	storeCost(int group, PlanCostEstimate cost)
void	storeStats(int groupId, PlanNodeStatsEstimate stats)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Memo

public Memo(PlanNodeIdAllocator idAllocator,
            PlanNode plan)

Method Detail

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 group,
                        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()