title: How large is a "buffer" in PostgreSQL
body: <p>I am using <code>pg_buffercache</code> module for finding hogs eating up my RAM cache. For example when I run this query:</p>
  
  <pre><code>SELECT c.relname, count(*) AS buffers
  FROM pg_buffercache b INNER JOIN pg_class c
      ON b.relfilenode = c.relfilenode AND
         b.reldatabase IN (0, (SELECT oid FROM pg_database WHERE datname = current_database()))
  GROUP BY c.relname
  ORDER BY 2 DESC
  LIMIT 10;
  </code></pre>
  
  <p>I discover that <code>sample_table</code> is using 120 buffers.</p>
  
  <p>How much is 120 buffers in bytes?</p>