text: -- +up
  CREATE TABLE `klines`
  (
      `gid`           BIGINT UNSIGNED         NOT NULL AUTO_INCREMENT,
      `exchange`      VARCHAR(10)             NOT NULL,
      `start_time`    DATETIME(3)             NOT NULL,
      `end_time`      DATETIME(3)             NOT NULL,
      `interval`      VARCHAR(3)              NOT NULL,
      `symbol`        VARCHAR(7)              NOT NULL,
      `open`          DECIMAL(16, 8) UNSIGNED NOT NULL,
      `high`          DECIMAL(16, 8) UNSIGNED NOT NULL,
      `low`           DECIMAL(16, 8) UNSIGNED NOT NULL,
      `close`         DECIMAL(16, 8) UNSIGNED NOT NULL DEFAULT 0.0,
      `volume`        DECIMAL(16, 8) UNSIGNED NOT NULL DEFAULT 0.0,
      `closed`        BOOL                    NOT NULL DEFAULT TRUE,
      `last_trade_id` INT UNSIGNED            NOT NULL DEFAULT 0,
      `num_trades`    INT UNSIGNED            NOT NULL DEFAULT 0,
  
      PRIMARY KEY (`gid`)
  
  );
  
  CREATE INDEX `klines_end_time_symbol_interval` ON klines (`end_time`, `symbol`, `interval`);
  CREATE TABLE `okex_klines` LIKE `klines`;
  CREATE TABLE `binance_klines` LIKE `klines`;
  CREATE TABLE `max_klines` LIKE `klines`;
  
  -- +down
  DROP INDEX `klines_end_time_symbol_interval` ON `klines`;
  DROP TABLE `binance_klines`;
  DROP TABLE `okex_klines`;
  DROP TABLE `max_klines`;
  DROP TABLE `klines`;
  
  