title: what data storage model is used to store articles in wikipedia
body: <p>Articles in wikipedia get edited. They can grow/shrink/updated etc. What file system/database storage layout etc is used underneath to support it. In database course, I had read a bit on variable length record, but that seemed like more for small strings and not for whole document. Like in file system, files can grow/shrink etc, and I think its done by chaining blocks together. each time, we update a file, not the whole file is rewritten. Perhaps something similar would be done here. </p>
  
  <p>I am looking for specific names,terminologies, may be even how the schema in mysql is defined. (I think wikipedia uses mysql).</p>
  
  <p>Below are links to some writeup on wikipedia architecture, but I am not being able to answer my question from these:</p>
  
  <p><a href="http://swe.web.cs.unibo.it/twiki/pub/WikiFactory/AntonelloDiMuroThesis/Wikipedia-cheapandexplosivescalingwithLAMP.pdf" rel="noreferrer">http://swe.web.cs.unibo.it/twiki/pub/WikiFactory/AntonelloDiMuroThesis/Wikipedia-cheapandexplosivescalingwithLAMP.pdf</a></p>
  
  <p><a href="http://dom.as/uc/workbook2007.pdf" rel="noreferrer">http://dom.as/uc/workbook2007.pdf</a></p>
  
  <p>Thanks,</p>