@Override
  public List<ForeignKey> getAdditionalForeignKeys(String schemaName, Database database)
      throws DatabaseException {
    List<ForeignKey> foreignKeys = super.getAdditionalForeignKeys(schemaName, database);

    // Setting default schema name. Needed for correct statement generation
    if (schemaName == null) {
      schemaName = database.convertRequestedSchemaToSchema(schemaName);
    }

    // Create SQL statement to select all FKs in database which referenced to unique columns
    String query =
        "select uc_fk.constraint_name FK_NAME,uc_fk.owner FKTABLE_SCHEM,ucc_fk.table_name FKTABLE_NAME,ucc_fk.column_name FKCOLUMN_NAME,decode(uc_fk.deferrable, 'DEFERRABLE', 5 ,'NOT DEFERRABLE', 7 , 'DEFERRED', 6 ) DEFERRABILITY, decode(uc_fk.delete_rule, 'CASCADE', 0,'NO ACTION', 3) DELETE_RULE,ucc_rf.table_name PKTABLE_NAME,ucc_rf.column_name PKCOLUMN_NAME from all_cons_columns ucc_fk,all_constraints uc_fk,all_cons_columns ucc_rf,all_constraints uc_rf where uc_fk.CONSTRAINT_NAME = ucc_fk.CONSTRAINT_NAME and uc_fk.constraint_type='R' and uc_fk.r_constraint_name=ucc_rf.CONSTRAINT_NAME and uc_rf.constraint_name = ucc_rf.constraint_name and uc_rf.constraint_type = 'U' and uc_fk.owner = '"
            + schemaName
            + "' and ucc_fk.owner = '"
            + schemaName
            + "' and uc_rf.owner = '"
            + schemaName
            + "' and ucc_rf.owner = '"
            + schemaName
            + "'";
    Statement statement = null;
    ResultSet rs = null;
    try {
      statement =
          ((JdbcConnection) database.getConnection()).getUnderlyingConnection().createStatement();
      rs = statement.executeQuery(query);
      while (rs.next()) {
        ForeignKeyInfo fkInfo = new ForeignKeyInfo();
        fkInfo.setReferencesUniqueColumn(true);
        fkInfo.setFkName(convertFromDatabaseName(rs.getString("FK_NAME")));
        fkInfo.setFkSchema(convertFromDatabaseName(rs.getString("FKTABLE_SCHEM")));
        fkInfo.setFkTableName(convertFromDatabaseName(rs.getString("FKTABLE_NAME")));
        fkInfo.setFkColumn(convertFromDatabaseName(rs.getString("FKCOLUMN_NAME")));

        fkInfo.setPkTableName(convertFromDatabaseName(rs.getString("PKTABLE_NAME")));
        fkInfo.setPkColumn(convertFromDatabaseName(rs.getString("PKCOLUMN_NAME")));

        fkInfo.setDeferrablility(rs.getShort("DEFERRABILITY"));
        ForeignKeyConstraintType deleteRule =
            convertToForeignKeyConstraintType(rs.getInt("DELETE_RULE"));
        if (rs.wasNull()) {
          deleteRule = null;
        }
        fkInfo.setDeleteRule(deleteRule);
        foreignKeys.add(generateForeignKey(fkInfo, database, foreignKeys));
      }
    } catch (SQLException e) {
      throw new DatabaseException(
          "Can't execute selection query to generate list of foreign keys", e);
    } finally {
      JdbcUtils.closeResultSet(rs);
      JdbcUtils.closeStatement(statement);
    }
    return foreignKeys;
  }
  @Override
  protected void readColumns(
      DatabaseSnapshot snapshot, String schema, DatabaseMetaData databaseMetaData)
      throws SQLException, DatabaseException {
    findIntegerColumns(snapshot, schema);
    super.readColumns(snapshot, schema, databaseMetaData);

    /*
     * Code Description:
     * Finding all 'tablespace' attributes of column's PKs
     * */
    Database database = snapshot.getDatabase();
    Statement statement = null;
    ResultSet rs = null;
    try {
      statement =
          ((JdbcConnection) database.getConnection()).getUnderlyingConnection().createStatement();

      // Setting default schema name. Needed for correct statement generation
      if (schema == null) schema = database.convertRequestedSchemaToSchema(schema);

      String query =
          "select ui.tablespace_name TABLESPACE, ucc.table_name TABLE_NAME, ucc.column_name COLUMN_NAME FROM all_indexes ui , all_constraints uc , all_cons_columns ucc where uc.constraint_type = 'P' and ucc.constraint_name = uc.constraint_name and uc.index_name = ui.index_name and uc.owner = '"
              + schema
              + "' and ui.table_owner = '"
              + schema
              + "' and ucc.owner = '"
              + schema
              + "'";
      rs = statement.executeQuery(query);

      while (rs.next()) {
        Column column = snapshot.getColumn(rs.getString("TABLE_NAME"), rs.getString("COLUMN_NAME"));
        // setting up tablespace property to column, to configure it's PK-index
        if (column == null) {
          continue; // probably a different schema
        }
        column.setTablespace(rs.getString("TABLESPACE"));
      }
    } finally {
      if (rs != null) {
        try {
          rs.close();
        } catch (SQLException ignore) {
        }
      }
      if (statement != null) {
        try {
          statement.close();
        } catch (SQLException ignore) {
        }
      }
    }
  }
  /**
   * Method finds all INTEGER columns in snapshot's database
   *
   * @param snapshot current database snapshot
   * @return String list with names of all INTEGER columns
   * @throws java.sql.SQLException execute statement error
   */
  private List<String> findIntegerColumns(DatabaseSnapshot snapshot, String schema)
      throws SQLException, DatabaseException {

    Database database = snapshot.getDatabase();
    // Setting default schema name. Needed for correct statement generation
    if (schema == null) {
      schema = database.convertRequestedSchemaToSchema(schema);
    }
    Statement statement =
        ((JdbcConnection) database.getConnection()).getUnderlyingConnection().createStatement();
    ResultSet integerListRS = null;
    // Finding all columns created as 'INTEGER'
    try {
      integerListRS =
          statement.executeQuery(
              "select TABLE_NAME, COLUMN_NAME from all_tab_columns where data_precision is null and data_scale = 0 and data_type = 'NUMBER' and owner = '"
                  + schema
                  + "'");
      while (integerListRS.next()) {
        integerList.add(
            integerListRS.getString("TABLE_NAME") + "." + integerListRS.getString("COLUMN_NAME"));
      }
    } finally {
      if (integerListRS != null) {
        try {
          integerListRS.close();
        } catch (SQLException ignore) {
        }
      }

      if (statement != null) {
        try {
          statement.close();
        } catch (SQLException ignore) {
        }
      }
    }

    return integerList;
  }
  @Override
  protected void readPrimaryKeys(
      DatabaseSnapshot snapshot, String schema, DatabaseMetaData databaseMetaData)
      throws DatabaseException, SQLException {
    Database database = snapshot.getDatabase();
    updateListeners("Reading primary keys for " + database.toString() + " ...");

    // we can't add directly to the this.primaryKeys hashSet because adding columns to an exising PK
    // changes the hashCode and .contains() fails
    List<PrimaryKey> foundPKs = new ArrayList<PrimaryKey>();
    // Setting default schema name. Needed for correct statement generation
    if (schema == null) schema = database.convertRequestedSchemaToSchema(schema);

    String query =
        "select uc.table_name TABLE_NAME,ucc.column_name COLUMN_NAME,ucc.position KEY_SEQ,uc.constraint_name PK_NAME,ui.tablespace_name TABLESPACE from all_constraints uc,all_indexes ui,all_cons_columns ucc where uc.constraint_type = 'P' and uc.index_name = ui.index_name and uc.constraint_name = ucc.constraint_name and uc.owner = '"
            + schema
            + "' and ui.table_owner = '"
            + schema
            + "' and ucc.owner = '"
            + schema
            + "' and uc.table_name = ui.table_name and ui.table_name = ucc.table_name";
    Statement statement = null;
    ResultSet rs = null;
    try {
      statement =
          ((JdbcConnection) database.getConnection()).getUnderlyingConnection().createStatement();
      rs = statement.executeQuery(query);

      while (rs.next()) {
        String tableName = convertFromDatabaseName(rs.getString("TABLE_NAME"));
        String tablespace = convertFromDatabaseName(rs.getString("TABLESPACE"));
        String columnName = convertFromDatabaseName(rs.getString("COLUMN_NAME"));
        short position = rs.getShort("KEY_SEQ");

        boolean foundExistingPK = false;
        for (PrimaryKey pk : foundPKs) {
          if (pk.getTable().getName().equals(tableName)) {
            pk.addColumnName(position - 1, columnName);

            foundExistingPK = true;
          }
        }

        if (!foundExistingPK && !database.isLiquibaseTable(tableName)) {
          PrimaryKey primaryKey = new PrimaryKey();
          primaryKey.setTablespace(tablespace);
          Table table = snapshot.getTable(tableName);
          if (table == null) {
            continue; // probably a different schema
          }
          primaryKey.setTable(table);
          primaryKey.addColumnName(position - 1, columnName);
          primaryKey.setName(convertPrimaryKeyName(rs.getString("PK_NAME")));

          foundPKs.add(primaryKey);
        }
      }
    } finally {
      JdbcUtils.closeResultSet(rs);
      JdbcUtils.closeStatement(statement);
    }

    snapshot.getPrimaryKeys().addAll(foundPKs);
  }
  @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);
        }
      }
    }
  }