public String getDBTime() throws MetaException {
    String s;
    switch (dbType) {
    case DERBY:
    case CUSTOM: // ANSI SQL
      s = "values current_timestamp";
      break;

    case MYSQL:
    case POSTGRES:
    case SQLSERVER:
      s = "select current_timestamp";
      break;

    case ORACLE:
      s = "select current_timestamp from dual";
      break;

    default:
      String msg = "Unknown database product: " + dbType.toString();
      LOG.error(msg);
      throw new MetaException(msg);
  }
    return s;
  }
Returns the query to fetch the current timestamp in milliseconds in the database
@throws MetaException when the dbType is unknown.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/DatabaseProduct.java