MergeLimits (presto-main 345 API)

java.lang.Object
- io.prestosql.sql.planner.iterative.rule.MergeLimits

All Implemented Interfaces:

Rule<LimitNode>
```
public class MergeLimits
extends Object
implements Rule<LimitNode>
```
This rule handles both LimitNode with ties and LimitNode without ties. The parent LimitNode is without ties.
If the child LimitNode is without ties, both nodes are merged into a single LimitNode with row count being the minimum of their row counts:
```
    - Limit (3)
       - Limit (5)
 
```
is transformed into:
```
     - Limit (3)
 
```
If the child LimitNode is with ties, the rule's behavior depends on both nodes' row count. If parent row count is lower or equal to child row count, child node is removed from the plan:
```
     - Limit (3)
        - Limit (5, withTies)
 
```
is transformed into:
```
     - Limit (3)
 
```
If parent row count is greater than child row count, both nodes remain in the plan, but they are rearranged in the way that the LimitNode with ties is the root:
```
     - Limit (5)
        - Limit (3, withTies)
 
```
is transformed into:
```
     - Limit (3, withTies)
        - Limit (5)
 
```

Nested Class Summary
- Nested classes/interfaces inherited from interface io.prestosql.sql.planner.iterative.Rule
  Rule.Context, Rule.Result

Constructor Summary

Constructors
Constructor Description

MergeLimits()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Rule.Result`	`apply(LimitNode parent, Captures captures, Rule.Context context)`
`Pattern<LimitNode>`	`getPattern()`	Returns a pattern to which plan nodes this rule applies.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.prestosql.sql.planner.iterative.Rule
isEnabled

Constructor Detail
- MergeLimits
```
public MergeLimits()
```

Method Detail

getPattern
```
public Pattern<LimitNode> getPattern()
```
Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<LimitNode>

apply

public Rule.Result apply(LimitNode parent,
                         Captures captures,
                         Rule.Context context)

Specified by:: apply in interface Rule<LimitNode>