   `articleItemType` VARCHAR(128) CHARACTER SET 'utf8' COLLATE 'utf8_unicode_ci' NOT NULL,
   `created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
   PRIMARY KEY (`itemId`),
+  KEY `doi` (`doi`),
   CONSTRAINT `fk_articleItem_1`
     FOREIGN KEY (`ingestionId`)
     REFERENCES `articleIngestion` (`ingestionId`)

  `fileSize` BIGINT NOT NULL,
  `created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`fileId`),
  CONSTRAINT `fk_articleFile_1`
    FOREIGN KEY (`ingestionId`)
    REFERENCES `articleIngestion` (`ingestionId`)

  `created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `lastModified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`ingestionId`),
  UNIQUE KEY `article_ingestnum` (`articleId`,`ingestionNumber`),
  CONSTRAINT `fk_articleIngestion_1`
    FOREIGN KEY (`articleId`)
    REFERENCES `article` (`articleId`)
