title: Storage engine for specific case
body: <p>What database can you recomend for such case:</p>
  
  <ol>
  <li>Very lot of inserts and updates</li>
  <li>Sophisticated queries (SQL or something like it)</li>
  <li>Lot of data, but small amount of frequently accessed (can be in memory)</li>
  <li>It's OK to loose part of data (recent hour for example) in case of crash (but not everything)</li>
  </ol>
  
  <p>Possible solutions and problems with it:</p>
  
  <ul>
  <li>Redis - looks good, but it doesn't support complex queries.</li>
  <li>RDBMS (current solution) - guarantee ACID and use hard disc a lot so updates is too slow</li>
  <li>RDBMS + RAM disc -  will use OS swap, recovery problems, and in general look not very reliable</li>
  <li>MongoDB - has server level lock on writes, is it really fast?</li>
  </ul>