anchor.diff:  For event correlation and root cause analysis it's not enough to find events that occur within the *same* ten second root event windows.
   What's needed is to find events that occur within a window of time *prior to each root event*.
   The `window` parameter allows you to specify this prior window of time as part of the query.
  -The window parameter is an integer which specifies the number of ten second time windows, prior to each root event window, to include in the graph walk.
  +The window parameter is an integer which specifies the number of ten second time windows,
  +prior to each root event window, to include in the graph walk.
   
   [source,text]
   ----
  
positive.code:             avg(qtime_i)),
              walk="time_ten_second_s->time_ten_second_s",
        gather="type_s",
        window="3",
        count(*))
  ----
  
  Below is the node set returned when the window parameter is added.
  Notice that there are *now 29 error* events within the 3 ten second windows prior to the slow query events.
  
negative.code:   }
  }
  ----
  
  === DAY and WEEKDAY Time Windows
  
  To switch to *day* or *weekday* time windows we must first index day truncated ISO 8601 timestamps in a string field with the log records.
  In the example below the field `time_day_s` contains the day truncated time stamps.
  
  Then its simply a matter of specifying -3DAYS in the window parameter. This will switch from the default ten second
  time windows to daily windows.
  
  [source,text]
  ----
  scoreNodes(nodes(solr_logs,
                   facet(solr_logs,
                         q="+type_s:query +distrib_s:false",
                         buckets="time_day_s",
                         avg(qtime_i)),
                   walk="time_day_s->time_day_s",
                   gather="type_s",
                   window="-3DAYS",
                   count(*)))
  ----
  
  There are times when you may need to skip the weekends when walking forwards or backwards in time. This is useful
  for correlating financial instruments that trade on weekdays. The WEEKDAYS time window will walk forward or backward the
  specified number of weekdays.
  
  [source,text]
  ----
  scoreNodes(nodes(solr_logs,
                   facet(solr_logs,
                         q="+type_s:query +distrib_s:false",
                         buckets="time_day_s",
                         avg(qtime_i)),
                   walk="time_day_s->time_day_s",
                   gather="type_s",
                   window="-3WEEKDAYS",
                   count(*)))
  ----
  
  
  
  