UnionMerger (Pinot local segment implementations 1.0.0 API)

java.lang.Object
- org.apache.pinot.segment.local.upsert.merger.UnionMerger

All Implemented Interfaces:

PartialUpsertMerger
```
public class UnionMerger
extends Object
implements PartialUpsertMerger
```
Merges 2 records and returns the merged record. Added the new value from incoming row to the existing value from multi-value field. Then return the merged record. Union merger will dedup duplicated records in the multi-value field.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Object`	`merge(Object previousValue, Object currentValue)`	Union the new value from incoming row to the given multi-value field of previous record.

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

- Method Detail
  - merge
```
public Object merge(Object previousValue,
                    Object currentValue)
```
    Union the new value from incoming row to the given multi-value field of previous record.
    
    Specified by:
    
    merge in interface PartialUpsertMerger
    
    Parameters:
    
    previousValue - the value of given field from the last derived full record during ingestion.
    
    currentValue - the value of given field from the new consumed record.
    
    Returns:
    
    a new value after merge