title: select longtext column too slow in mysql
body: <p>I have a table like below,</p>
  
  <pre><code>CREATE TABLE `floor` (
    `id` bigint(11) NOT NULL AUTO_INCREMENT,
    `floorName` varchar(20) NOT NULL,
    `buildingId` bigint(11) NOT NULL,
    `imageInString` longtext,
    `image` longtext,
    PRIMARY KEY (`id`),
    KEY `fk_floor_1_idx` (`buildingId`),
    CONSTRAINT `fk_floor_1` FOREIGN KEY (`buildingId`) REFERENCES `building` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
  ) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=latin1;
  </code></pre>
  
  <p>table contains 20 rows. I am inserting images(SVG/JPEG) as base64 in the <strong>image</strong> column.</p>
  
  <p>when I select different size of inserted column it takes, </p>
  
  <pre><code>4KB -&gt; Loaded less than 1 sec
  
  200KB -&gt; 3 to 4 secs
  
  500KB -&gt; 8 secs
  
  3MB   -&gt; 30 to 50 secs
  </code></pre>
  
  <p>Here is my dealing, I want to load the 3MB file in 1 to 2 secs.</p>
  
  <p>How can achieve this?</p>