title: Earliest Timestamp supported in PostgreSQL
body: <p>I work with different databases in a number of different time zones (and periods of time) and one thing that normally originates problems, is the date/time definition.</p>
  
  <p>For this reason, and since a date is a reference to a starting value, to keep track of how it was calculated, I try to store the base date; i.e.: the minimum date supported in that particular computer/database;</p>
  
  <p>If I am seeing it well, this depends on the RDBMS and on the particular storage of the type.
  In SQL Server, I found a couple of ways of calculating this "base date";</p>
  
  <pre><code>SELECT CONVERT(DATETIME, 0) 
  </code></pre>
  
  <p>or</p>
  
  <pre><code>SELECT DATEADD(MONTH, 0, 0 ) 
  </code></pre>
  
  <p>or even a cast like this:</p>
  
  <pre><code>DECLARE @300 BINARY(8) 
  SET @300 = 0x00000000 + CAST(300 AS BINARY(4))
  set @dt=(SELECT CAST(@300 AS DATETIME) AS BASEDATE)
  print CAST(@dt AS NVARCHAR(100))
  </code></pre>
  
  <p>(where @dt is a datetime variable)</p>
  
  <p>My question is, is there a similar way of calculating the base date in PostgreSQL, i.e.: the value that is the minimum date supported and is on the base of all calculations?</p>
  
  <p>From the description of the <a href="http://www.postgresql.org/docs/current/static/datatype-datetime.html" rel="noreferrer"><code>date</code> type</a>, I can see that the minimum date supported is 4713 BC, but is there a way of getting this value programmatically (for instance as a formatted date string), as I do in SQL Server?</p>