title: postgresql 9.2 never vacuumed and analyze
body: <p>I have given a postgres 9.2 DB around 20GB of size.</p>
  
  <p>I looked through the database and saw that it has been never run vacuum and/or analyze on any tables. 
  Autovacuum is on and the transaction wraparound limit is very far (only 1% of it). </p>
  
  <p>I know nothing about the data activity (number of deletes,inserts, updates), but I see, it uses a lot of index and sequence.
  My question is:</p>
  
  <ol>
  <li><p>does the lack of vacuum and/or analyze affect data integrity (for example a select doesn't show all the rows matches the select from a table or from an index)? The speed of querys and writes doesn't matter.</p></li>
  <li><p>is it possible that after the vacuum and/or analyze the same query gives a different answer than it would executed before the vacuum/analyze command?</p></li>
  </ol>
  
  <p>I'm fairly new to PG, thank you for your help!!</p>
  
  <p>Regards,
  Figaro88</p>