title: Graylog alerting on specific log occurrence
body: <p>I have a question on how does one set up an email alert, when a certain error in found in the logs.
  So basicly i have this sort of error :
  org.postgresql.util.PSQLException: ERROR: missing FROM-clause entry for table &quot;something&quot;.</p>
  <p>Now when this error, or similar error comes, i would love for graylog to alert certain people so they can react to it, however i have managed to only find information on how you set up alerts when there are too many messages coming through or something like that. If anyone has some experience with this sort of search and notify alert, would be much appreciated.</p>