@Override
  public Change[] fixMissing(
      DatabaseObject missingObject,
      DiffOutputControl control,
      Database referenceDatabase,
      Database comparisonDatabase,
      ChangeGeneratorChain chain) {
    List<Change> returnList = new ArrayList<Change>();

    UniqueConstraint uc = (UniqueConstraint) missingObject;

    if (uc.getTable() == null) {
      return null;
    }

    AddUniqueConstraintChange change = new AddUniqueConstraintChange();
    change.setTableName(uc.getTable().getName());
    if (uc.getBackingIndex() != null && control.getIncludeTablespace()) {
      change.setTablespace(uc.getBackingIndex().getTablespace());
    }
    if (control.getIncludeCatalog()) {
      change.setCatalogName(uc.getTable().getSchema().getCatalogName());
    }
    if (control.getIncludeSchema()) {
      change.setSchemaName(uc.getTable().getSchema().getName());
    }
    change.setConstraintName(uc.getName());
    change.setColumnNames(uc.getColumnNames());
    change.setDeferrable(uc.isDeferrable() ? Boolean.TRUE : null);
    change.setInitiallyDeferred(uc.isInitiallyDeferred() ? Boolean.TRUE : null);
    change.setDisabled(uc.isDisabled() ? Boolean.TRUE : null);

    if (comparisonDatabase instanceof OracleDatabase) {
      Index backingIndex = uc.getBackingIndex();
      if (backingIndex != null && backingIndex.getName() != null) {
        Change[] changes =
            ChangeGeneratorFactory.getInstance()
                .fixMissing(backingIndex, control, referenceDatabase, comparisonDatabase);
        if (changes != null) {
          returnList.addAll(Arrays.asList(changes));

          change.setForIndexName(backingIndex.getName());
          Schema schema = backingIndex.getSchema();
          if (schema != null) {
            if (control.getIncludeCatalog()) {
              change.setForIndexCatalogName(schema.getCatalogName());
            }
            if (control.getIncludeSchema()) {
              change.setForIndexSchemaName(schema.getName());
            }
          }
        }
      }
    }

    Index backingIndex = uc.getBackingIndex();
    //        if (backingIndex == null) {
    //            Index exampleIndex = new Index().setTable(uc.getTable());
    //            for (String col : uc.getColumns()) {
    //                exampleIndex.getColumns().add(col);
    //            }
    //            control.setAlreadyHandledMissing(exampleIndex);
    //        } else {
    control.setAlreadyHandledMissing(backingIndex);
    //        }

    returnList.add(change);

    return returnList.toArray(new Change[returnList.size()]);
  }
  @Override
  protected void readIndexes(
      DatabaseSnapshot snapshot, String schema, DatabaseMetaData databaseMetaData)
      throws DatabaseException, SQLException {
    Database database = snapshot.getDatabase();
    updateListeners("Reading indexes for " + database.toString() + " ...");

    String query =
        "select aic.index_name, 3 AS TYPE, aic.table_name, aic.column_name, aic.column_position AS ORDINAL_POSITION, null AS FILTER_CONDITION, ai.tablespace_name AS TABLESPACE, ai.uniqueness FROM all_ind_columns aic, all_indexes ai WHERE aic.table_owner='"
            + database.convertRequestedSchemaToSchema(schema)
            + "' and aic.index_name = ai.index_name ORDER BY INDEX_NAME, ORDINAL_POSITION";
    Statement statement = null;
    ResultSet rs = null;
    Map<String, Index> indexMap = null;
    try {
      statement =
          ((JdbcConnection) database.getConnection()).getUnderlyingConnection().createStatement();
      rs = statement.executeQuery(query);

      indexMap = new HashMap<String, Index>();
      while (rs.next()) {
        String indexName = convertFromDatabaseName(rs.getString("INDEX_NAME"));
        String tableName = rs.getString("TABLE_NAME");
        String tableSpace = rs.getString("TABLESPACE");
        String columnName = convertFromDatabaseName(rs.getString("COLUMN_NAME"));
        if (columnName == null) {
          // nothing to index, not sure why these come through sometimes
          continue;
        }
        short type = rs.getShort("TYPE");

        boolean nonUnique;

        String uniqueness = rs.getString("UNIQUENESS");

        if ("UNIQUE".equals(uniqueness)) {
          nonUnique = false;
        } else {
          nonUnique = true;
        }

        short position = rs.getShort("ORDINAL_POSITION");
        String filterCondition = rs.getString("FILTER_CONDITION");

        if (type == DatabaseMetaData.tableIndexStatistic) {
          continue;
        }

        Index index;
        if (indexMap.containsKey(indexName)) {
          index = indexMap.get(indexName);
        } else {
          index = new Index();
          Table table = snapshot.getTable(tableName);
          if (table == null) {
            continue; // probably different schema
          }
          index.setTable(table);
          index.setTablespace(tableSpace);
          index.setName(indexName);
          index.setUnique(!nonUnique);
          index.setFilterCondition(filterCondition);
          indexMap.put(indexName, index);
        }

        for (int i = index.getColumns().size(); i < position; i++) {
          index.getColumns().add(null);
        }
        index.getColumns().set(position - 1, columnName);
      }
    } finally {
      JdbcUtils.closeResultSet(rs);
      JdbcUtils.closeStatement(statement);
    }

    for (Map.Entry<String, Index> entry : indexMap.entrySet()) {
      snapshot.getIndexes().add(entry.getValue());
    }

    /*
     * marks indexes as "associated with" instead of "remove it"
     * Index should have associations with:
     * foreignKey, primaryKey or uniqueConstraint
     * */
    for (Index index : snapshot.getIndexes()) {
      for (PrimaryKey pk : snapshot.getPrimaryKeys()) {
        if (index.getTable().getName().equalsIgnoreCase(pk.getTable().getName())
            && index.getColumnNames().equals(pk.getColumnNames())) {
          index.addAssociatedWith(Index.MARK_PRIMARY_KEY);
        }
      }
      for (ForeignKey fk : snapshot.getForeignKeys()) {
        if (index.getTable().getName().equalsIgnoreCase(fk.getForeignKeyTable().getName())
            && index.getColumnNames().equals(fk.getForeignKeyColumns())) {
          index.addAssociatedWith(Index.MARK_FOREIGN_KEY);
        }
      }
      for (UniqueConstraint uc : snapshot.getUniqueConstraints()) {
        if (index.getTable().getName().equalsIgnoreCase(uc.getTable().getName())
            && index.getColumnNames().equals(uc.getColumnNames())) {
          index.addAssociatedWith(Index.MARK_UNIQUE_CONSTRAINT);
        }
      }
    }
  }