Deduper (Atlassian Confluence 8.5.7 API)

java.lang.Object
- com.atlassian.confluence.internal.upgrade.constraint.dedup.Deduper

```
public class Deduper
extends Object
```
Remove duplicated rows from a table before a unique constraint can be added. This is a 2-step process: 1. Query all duplicate rows 2. Use a suitable DedupeStrategy to delete those duplicates Note: 1. Tables with composite keys are not supported. 2. This implementation doesn't scale well because it puts everything in memory and process DMLs one at a time

Since:

7.1.0

Constructor Summary

Constructors
Constructor Description

Deduper(org.hibernate.SessionFactory sessionFactory, com.atlassian.config.db.HibernateConfig hibernateConfig)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`multipleNullsNotAllowed()`	Oracle and SQL Server behave differently from the rest: two rows that contain nulls for one or more key columns and the same combination of values for the other key columns violate a unique constraint.
`long`	`removeDuplicates(String table, String idColumn, List<String> uniqueColumns, DedupeStrategy dedupeStrategy)`	Remove all duplicates of combination of `uniqueColumns` from `table`.

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

- Constructor Detail
  - Deduper
```
public Deduper(org.hibernate.SessionFactory sessionFactory,
               com.atlassian.config.db.HibernateConfig hibernateConfig)
```
- Method Detail
  - removeDuplicates
```
public long removeDuplicates(String table,
                             String idColumn,
                             List<String> uniqueColumns,
                             DedupeStrategy dedupeStrategy)
                      throws UpgradeException
```
    Remove all duplicates of combination of uniqueColumns from table. Note: names of tables and columns are not to be quoted.
    
    Returns:
    
    number of duplicate rows removed
    
    Throws:
    
    UpgradeException
  - multipleNullsNotAllowed
```
public boolean multipleNullsNotAllowed()
```
    Oracle and SQL Server behave differently from the rest: two rows that contain nulls for one or more key columns and the same combination of values for the other key columns violate a unique constraint.
    
    Returns:
    
    true if current SQL vendor doesn't accepts multiple null values in multi-column unique constraints