title: Logstash jdbc-input-plugin configuration for initial sql_last_value
body: <p>I synchronise data in Oracle database and ElasticSearch instance.<br>
  Database table <code>"SYNC_TABLE"</code> has the following columns: <code>"ID"</code> which is a NUMBER, <code>"LAST_MODIFICATION"</code> - TIMESTAMP, <code>"TEXT"</code> - VARCHAR2.</p>
  
  <p>I use Logstash with jdbc-input-plugin in order to perform data syncronisation on a regular basis.</p>
  
  <p>This is the Logstash configuration file:</p>
  
  <pre><code>input { 
    jdbc {
      jdbc_driver_library =&gt; "ojdbc6.jar"
      jdbc_driver_class =&gt; "Java::oracle.jdbc.driver.OracleDriver"
      jdbc_connection_string =&gt; "jdbc:oracle:thin:@localhost:1521:XE"
      jdbc_user =&gt; "******"
      jdbc_password =&gt; "******"
      schedule =&gt; "* * * * *"
      statement =&gt; "SELECT * from SYNC_TABLE where LAST_MODIFICATION &gt;= :sql_last_value"
      tracking_column =&gt; "LAST_MODIFICATION"
      tracking_column_type =&gt; "timestamp"
      use_column_value =&gt; true
    }
  }
  output {
    elasticsearch { 
      index =&gt; "SYNC_TABLE"
      document_type =&gt; "SYNCED_DATA"
      document_id =&gt; "%{ID}"
      hosts =&gt; "localhost:9200"
    }
    stdout { codec =&gt; rubydebug }
  }
  </code></pre>
  
  <p>I'd like to import all the data on the first run and then syncronise only diff between the last run and current time.
  So I expect Logstash to make the following queries:</p>
  
  <pre><code>SELECT * from SYNC_TABLE where LAST_MODIFICATION &gt;= '1 January 1970 00:00'
  </code></pre>
  
  <p>and then regularly</p>
  
  <pre><code>SELECT * from SYNC_TABLE where LAST_MODIFICATION &gt;= 'time of last run'
  </code></pre>
  
  <p><a href="https://www.elastic.co/guide/en/logstash/current/plugins-inputs-jdbc.html#_predefined_parameters" rel="nofollow noreferrer">Documentation</a> says that initial value for should be 1 January 1970, but I see in my logs that instead it takes current timestamp.
  This is the first query:</p>
  
  <pre><code>SELECT * from SYNC_TABLE where LAST_MODIFICATION &gt;= TIMESTAMP '2017-08-14 09:17:00.481000 +00:00'
  </code></pre>
  
  <p>Is there any mistake in logstash configuration file that makes the logstash use current timestamp instead of default ('1 January 1970 00:00')?</p>