@Override
 public int update() {
   session.commit(true);
   Database db = session.getDatabase();
   Schema schema = oldIndex.getSchema();
   if (schema.findIndex(session, newIndexName) != null
       || newIndexName.equals(oldIndex.getName())) {
     throw DbException.get(ErrorCode.INDEX_ALREADY_EXISTS_1, newIndexName);
   }
   session.getUser().checkRight(oldIndex.getTable(), Right.ALL);
   db.renameSchemaObject(session, oldIndex, newIndexName);
   return 0;
 }
 public int update() {
   session.commit(true);
   Database db = session.getDatabase();
   session.getUser().checkRight(table, Right.ALL);
   table.checkSupportAlter();
   table.renameColumn(column, newName);
   table.setModified();
   db.update(session, table);
   for (DbObject child : table.getChildren()) {
     if (child.getCreateSQL() != null) {
       db.update(session, child);
     }
   }
   return 0;
 }
  @Override
  public ResultInterface query(int maxrows) {
    session.getUser().checkAdmin();
    reset();
    Database db = session.getDatabase();
    if (schemaNames != null) {
      for (String schemaName : schemaNames) {
        Schema schema = db.findSchema(schemaName);
        if (schema == null) {
          throw DbException.get(ErrorCode.SCHEMA_NOT_FOUND_1, schemaName);
        }
      }
    }
    try {
      result = createResult();
      deleteStore();
      openOutput();
      if (out != null) {
        buffer = new byte[Constants.IO_BUFFER_SIZE];
      }
      if (settings) {
        for (Setting setting : db.getAllSettings()) {
          if (setting.getName().equals(SetTypes.getTypeName(SetTypes.CREATE_BUILD))) {
            // don't add CREATE_BUILD to the script
            // (it is only set when creating the database)
            continue;
          }
          add(setting.getCreateSQL(), false);
        }
      }
      if (out != null) {
        add("", true);
      }
      for (User user : db.getAllUsers()) {
        add(user.getCreateSQL(passwords), false);
      }
      for (Role role : db.getAllRoles()) {
        add(role.getCreateSQL(true), false);
      }
      for (Schema schema : db.getAllSchemas()) {
        if (excludeSchema(schema)) {
          continue;
        }
        add(schema.getCreateSQL(), false);
      }
      for (UserDataType datatype : db.getAllUserDataTypes()) {
        if (drop) {
          add(datatype.getDropSQL(), false);
        }
        add(datatype.getCreateSQL(), false);
      }
      for (SchemaObject obj : db.getAllSchemaObjects(DbObject.CONSTANT)) {
        if (excludeSchema(obj.getSchema())) {
          continue;
        }
        Constant constant = (Constant) obj;
        add(constant.getCreateSQL(), false);
      }

      final ArrayList<Table> tables = db.getAllTablesAndViews(false);
      // sort by id, so that views are after tables and views on views
      // after the base views
      Collections.sort(
          tables,
          new Comparator<Table>() {
            @Override
            public int compare(Table t1, Table t2) {
              return t1.getId() - t2.getId();
            }
          });

      // Generate the DROP XXX ... IF EXISTS
      for (Table table : tables) {
        if (excludeSchema(table.getSchema())) {
          continue;
        }
        if (excludeTable(table)) {
          continue;
        }
        if (table.isHidden()) {
          continue;
        }
        table.lock(session, false, false);
        String sql = table.getCreateSQL();
        if (sql == null) {
          // null for metadata tables
          continue;
        }
        if (drop) {
          add(table.getDropSQL(), false);
        }
      }
      for (SchemaObject obj : db.getAllSchemaObjects(DbObject.FUNCTION_ALIAS)) {
        if (excludeSchema(obj.getSchema())) {
          continue;
        }
        if (drop) {
          add(obj.getDropSQL(), false);
        }
        add(obj.getCreateSQL(), false);
      }
      for (UserAggregate agg : db.getAllAggregates()) {
        if (drop) {
          add(agg.getDropSQL(), false);
        }
        add(agg.getCreateSQL(), false);
      }
      for (SchemaObject obj : db.getAllSchemaObjects(DbObject.SEQUENCE)) {
        if (excludeSchema(obj.getSchema())) {
          continue;
        }
        Sequence sequence = (Sequence) obj;
        if (drop) {
          add(sequence.getDropSQL(), false);
        }
        add(sequence.getCreateSQL(), false);
      }

      // Generate CREATE TABLE and INSERT...VALUES
      int count = 0;
      for (Table table : tables) {
        if (excludeSchema(table.getSchema())) {
          continue;
        }
        if (excludeTable(table)) {
          continue;
        }
        if (table.isHidden()) {
          continue;
        }
        table.lock(session, false, false);
        String createTableSql = table.getCreateSQL();
        if (createTableSql == null) {
          // null for metadata tables
          continue;
        }
        final String tableType = table.getTableType();
        add(createTableSql, false);
        final ArrayList<Constraint> constraints = table.getConstraints();
        if (constraints != null) {
          for (Constraint constraint : constraints) {
            if (Constraint.PRIMARY_KEY.equals(constraint.getConstraintType())) {
              add(constraint.getCreateSQLWithoutIndexes(), false);
            }
          }
        }
        if (Table.TABLE.equals(tableType)) {
          if (table.canGetRowCount()) {
            String rowcount =
                "-- "
                    + table.getRowCountApproximation()
                    + " +/- SELECT COUNT(*) FROM "
                    + table.getSQL();
            add(rowcount, false);
          }
          if (data) {
            count = generateInsertValues(count, table);
          }
        }
        final ArrayList<Index> indexes = table.getIndexes();
        for (int j = 0; indexes != null && j < indexes.size(); j++) {
          Index index = indexes.get(j);
          if (!index.getIndexType().getBelongsToConstraint()) {
            add(index.getCreateSQL(), false);
          }
        }
      }
      if (tempLobTableCreated) {
        add("DROP TABLE IF EXISTS SYSTEM_LOB_STREAM", true);
        add("CALL SYSTEM_COMBINE_BLOB(-1)", true);
        add("DROP ALIAS IF EXISTS SYSTEM_COMBINE_CLOB", true);
        add("DROP ALIAS IF EXISTS SYSTEM_COMBINE_BLOB", true);
        tempLobTableCreated = false;
      }
      // Generate CREATE CONSTRAINT ...
      final ArrayList<SchemaObject> constraints = db.getAllSchemaObjects(DbObject.CONSTRAINT);
      Collections.sort(
          constraints,
          new Comparator<SchemaObject>() {
            @Override
            public int compare(SchemaObject c1, SchemaObject c2) {
              return ((Constraint) c1).compareTo((Constraint) c2);
            }
          });
      for (SchemaObject obj : constraints) {
        if (excludeSchema(obj.getSchema())) {
          continue;
        }
        Constraint constraint = (Constraint) obj;
        if (excludeTable(constraint.getTable())) {
          continue;
        }
        if (constraint.getTable().isHidden()) {
          continue;
        }
        if (!Constraint.PRIMARY_KEY.equals(constraint.getConstraintType())) {
          add(constraint.getCreateSQLWithoutIndexes(), false);
        }
      }
      // Generate CREATE TRIGGER ...
      for (SchemaObject obj : db.getAllSchemaObjects(DbObject.TRIGGER)) {
        if (excludeSchema(obj.getSchema())) {
          continue;
        }
        TriggerObject trigger = (TriggerObject) obj;
        if (excludeTable(trigger.getTable())) {
          continue;
        }
        add(trigger.getCreateSQL(), false);
      }
      // Generate GRANT ...
      for (Right right : db.getAllRights()) {
        Table table = right.getGrantedTable();
        if (table != null) {
          if (excludeSchema(table.getSchema())) {
            continue;
          }
          if (excludeTable(table)) {
            continue;
          }
        }
        add(right.getCreateSQL(), false);
      }
      // Generate COMMENT ON ...
      for (Comment comment : db.getAllComments()) {
        add(comment.getCreateSQL(), false);
      }
      if (out != null) {
        out.close();
      }
    } catch (IOException e) {
      throw DbException.convertIOException(e, getFileName());
    } finally {
      closeIO();
    }
    result.done();
    LocalResult r = result;
    reset();
    return r;
  }
 /**
  * Try to execute the statement.
  *
  * @return the update count
  */
 private int tryUpdate() {
   if (!transactional) {
     session.commit(true);
   }
   Database db = session.getDatabase();
   Table table = getSchema().getTableOrView(session, tableName);
   if (getSchema().findConstraint(session, constraintName) != null) {
     if (ifNotExists) {
       return 0;
     }
     throw DbException.get(ErrorCode.CONSTRAINT_ALREADY_EXISTS_1, constraintName);
   }
   session.getUser().checkRight(table, Right.ALL);
   db.lockMeta(session);
   table.lock(session, true, true);
   Constraint constraint;
   switch (type) {
     case CommandInterface.ALTER_TABLE_ADD_CONSTRAINT_PRIMARY_KEY:
       {
         IndexColumn.mapColumns(indexColumns, table);
         index = table.findPrimaryKey();
         ArrayList<Constraint> constraints = table.getConstraints();
         for (int i = 0; constraints != null && i < constraints.size(); i++) {
           Constraint c = constraints.get(i);
           if (Constraint.PRIMARY_KEY.equals(c.getConstraintType())) {
             throw DbException.get(ErrorCode.SECOND_PRIMARY_KEY);
           }
         }
         if (index != null) {
           // if there is an index, it must match with the one declared
           // we don't test ascending / descending
           IndexColumn[] pkCols = index.getIndexColumns();
           if (pkCols.length != indexColumns.length) {
             throw DbException.get(ErrorCode.SECOND_PRIMARY_KEY);
           }
           for (int i = 0; i < pkCols.length; i++) {
             if (pkCols[i].column != indexColumns[i].column) {
               throw DbException.get(ErrorCode.SECOND_PRIMARY_KEY);
             }
           }
         }
         if (index == null) {
           IndexType indexType =
               IndexType.createPrimaryKey(table.isPersistIndexes(), primaryKeyHash);
           String indexName =
               table.getSchema().getUniqueIndexName(session, table, Constants.PREFIX_PRIMARY_KEY);
           int id = getObjectId();
           try {
             index = table.addIndex(session, indexName, id, indexColumns, indexType, true, null);
           } finally {
             getSchema().freeUniqueName(indexName);
           }
         }
         index.getIndexType().setBelongsToConstraint(true);
         int constraintId = getObjectId();
         String name = generateConstraintName(table);
         ConstraintUnique pk = new ConstraintUnique(getSchema(), constraintId, name, table, true);
         pk.setColumns(indexColumns);
         pk.setIndex(index, true);
         constraint = pk;
         break;
       }
     case CommandInterface.ALTER_TABLE_ADD_CONSTRAINT_UNIQUE:
       {
         IndexColumn.mapColumns(indexColumns, table);
         boolean isOwner = false;
         if (index != null && canUseUniqueIndex(index, table, indexColumns)) {
           isOwner = true;
           index.getIndexType().setBelongsToConstraint(true);
         } else {
           index = getUniqueIndex(table, indexColumns);
           if (index == null) {
             index = createIndex(table, indexColumns, true);
             isOwner = true;
           }
         }
         int id = getObjectId();
         String name = generateConstraintName(table);
         ConstraintUnique unique = new ConstraintUnique(getSchema(), id, name, table, false);
         unique.setColumns(indexColumns);
         unique.setIndex(index, isOwner);
         constraint = unique;
         break;
       }
     case CommandInterface.ALTER_TABLE_ADD_CONSTRAINT_CHECK:
       {
         int id = getObjectId();
         String name = generateConstraintName(table);
         ConstraintCheck check = new ConstraintCheck(getSchema(), id, name, table);
         TableFilter filter = new TableFilter(session, table, null, false, null);
         checkExpression.mapColumns(filter, 0);
         checkExpression = checkExpression.optimize(session);
         check.setExpression(checkExpression);
         check.setTableFilter(filter);
         constraint = check;
         if (checkExisting) {
           check.checkExistingData(session);
         }
         break;
       }
     case CommandInterface.ALTER_TABLE_ADD_CONSTRAINT_REFERENTIAL:
       {
         Table refTable = refSchema.getTableOrView(session, refTableName);
         session.getUser().checkRight(refTable, Right.ALL);
         if (!refTable.canReference()) {
           throw DbException.get(
               ErrorCode.FEATURE_NOT_SUPPORTED_1, "Reference " + refTable.getSQL());
         }
         boolean isOwner = false;
         IndexColumn.mapColumns(indexColumns, table);
         if (index != null && canUseIndex(index, table, indexColumns)) {
           isOwner = true;
           index.getIndexType().setBelongsToConstraint(true);
         } else {
           index = getIndex(table, indexColumns);
           if (index == null) {
             index = createIndex(table, indexColumns, false);
             isOwner = true;
           }
         }
         if (refIndexColumns == null) {
           Index refIdx = refTable.getPrimaryKey();
           refIndexColumns = refIdx.getIndexColumns();
         } else {
           IndexColumn.mapColumns(refIndexColumns, refTable);
         }
         if (refIndexColumns.length != indexColumns.length) {
           throw DbException.get(ErrorCode.COLUMN_COUNT_DOES_NOT_MATCH);
         }
         boolean isRefOwner = false;
         if (refIndex != null
             && refIndex.getTable() == refTable
             && canUseIndex(refIndex, refTable, refIndexColumns)) {
           isRefOwner = true;
           refIndex.getIndexType().setBelongsToConstraint(true);
         } else {
           refIndex = null;
         }
         if (refIndex == null) {
           refIndex = getIndex(refTable, refIndexColumns);
           if (refIndex == null) {
             refIndex = createIndex(refTable, refIndexColumns, true);
             isRefOwner = true;
           }
         }
         int id = getObjectId();
         String name = generateConstraintName(table);
         ConstraintReferential ref = new ConstraintReferential(getSchema(), id, name, table);
         ref.setColumns(indexColumns);
         ref.setIndex(index, isOwner);
         ref.setRefTable(refTable);
         ref.setRefColumns(refIndexColumns);
         ref.setRefIndex(refIndex, isRefOwner);
         if (checkExisting) {
           ref.checkExistingData(session);
         }
         constraint = ref;
         refTable.addConstraint(constraint);
         ref.setDeleteAction(deleteAction);
         ref.setUpdateAction(updateAction);
         break;
       }
     default:
       throw DbException.throwInternalError("type=" + type);
   }
   // parent relationship is already set with addConstraint
   constraint.setComment(comment);
   if (table.isTemporary() && !table.isGlobalTemporary()) {
     session.addLocalTempTableConstraint(constraint);
   } else {
     db.addSchemaObject(session, constraint);
   }
   table.addConstraint(constraint);
   return 0;
 }