title: MySQL, CONCAT, the result is null after a while
body: <p>Im putting big data to table, to a <code>LONGBLOB</code> field, but as the table grows, the field becomes empty. Code:</p>
  
  <pre><code>mysql_query ('CREATE TABLE IF NOT EXISTS testtable (content LONGBLOB NOT NULL) ENGINE = MyISAM');
  mysql_query('TRUNCATE TABLE testtable');
  mysql_query('REPLACE INTO testtable VALUES (".")');
  $bigData = str_repeat('A', 1024*1024*2); // 2 MB!
  foreach (str_split($bigData, 1024*64) as $item)
  {
      mysql_query ('UPDATE testtable SET content = CONCAT(content, "'.mysql_real_escape_string($item).'")');
      $rec = mysql_fetch_row(mysql_query ('SELECT content FROM testtable'));
      echo 'Size of the content: '.strlen($rec[0]).'&lt;br&gt;';
  }
  </code></pre>
  
  <p>The output:</p>
  
  <pre><code>Size of the content: 65537
  Size of the content: 131073
  Size of the content: 196609
  Size of the content: 262145
  Size of the content: 327681
  Size of the content: 393217
  Size of the content: 458753
  Size of the content: 524289
  Size of the content: 589825
  Size of the content: 655361
  Size of the content: 720897
  Size of the content: 786433
  Size of the content: 851969
  Size of the content: 917505
  Size of the content: 983041
  Size of the content: 0
  Size of the content: 65536
  Size of the content: 131072
  Size of the content: 196608
  </code></pre>
  
  <p>Whats happening? LONGBLOB should take more data than that.</p>