title: Postgresql vs. MySQL: how do their data sizes compare to each other?
body: <p>For the same data set, with mostly text data, how do the data (table + index) size of Postgresql compared to that of MySQL?</p>
  
  <ul>
  <li><p>Postgresql uses MVCC, that would suggest its data size would be bigger</p></li>
  <li><p>In this presentation, the largest blog site in Japan talked about their migration from Postgresql to MySQL. One of their reasons for moving away from Postgresql was that data size in Postgresql was too large (p. 41):
  <a href="http://www.scribd.com/doc/2569473/Migrating-from-PostgreSQL-to-MySQL-at-Cocolog-Japans-Largest-Blog-Community" rel="noreferrer">Migrating from PostgreSQL to MySQL at Cocolog, Japan's Largest Blog Community</a></p></li>
  <li><p>Postgresql has data compression, so that should make the data size smaller. But MySQL Plugin also has compression. </p></li>
  </ul>
  
  <p>Does anyone have any actual experience about how the data sizes of Postgresql &amp; MySQL compare to each other?</p>