title: How much disk-space is needed to store a NULL value using postgresql DB?
body: <p>let's say I have a column on my table defined the following:</p>
  
  <pre><code>"MyColumn" smallint NULL
  </code></pre>
  
  <p>Storing a value like 0, 1 or something else should need 2 bytes (1). But how much space is needed if I set "MyColumn" to NULL? Will it need 0 bytes?</p>
  
  <p>Are there some additional needed bytes for administration purpose or such things for every column/row?</p>
  
  <p>(1) <a href="http://www.postgresql.org/docs/9.0/interactive/datatype-numeric.html" rel="noreferrer">http://www.postgresql.org/docs/9.0/interactive/datatype-numeric.html</a></p>