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Session: Patch Time Series



Patching Using session.Advanced.Defer

  • Defer is used for patching in general, not necessarily for time series data patching.
  • To patch time series data, you need to customize the JavaScript that Defer uses.
  • Learn more about time series JavaScript here.

Syntax

  • PatchCommandData

    • Definition
      public PatchCommandData(string id, string changeVector, 
          PatchRequest patch, PatchRequest patchIfMissing)
      Learn more about PatchCommandData here.
  • PatchRequest

    • Definition
      private class PatchRequest
      {
          // Patching script
          public string Script { get; set; }
          // Values that can be used by the patching script
          public Dictionary<string, object> Values { get; set; }
          //...
      }
      Learn more about PatchRequest here.

Usage Flow

  • Open a session
  • Call session.Advanced.Defer and pass it a PatchCommandData instance.
  • Pass the PatchCommandData constructor method -
    • the document ID
    • the change vector (or null)
    • a PatchRequest instance with a JavaScript that appends or removes time series entries.
  • Call session.SaveChanges() to perform the patch.

Usage Samples

  • In this sample, we pass Defer a script that appends a document 100 time series entries with random heart rate values.

    var baseline = DateTime.Today;
    
    // Create arrays of timestamps and random values to patch
    List<double> values = new List<double>();
    List<DateTime> timeStamps = new List<DateTime>();
    
    for (var cnt = 0; cnt < 100; cnt++)
    {
        values.Add(68 + Math.Round(19 * new Random().NextDouble()));
        timeStamps.Add(baseline.AddSeconds(cnt));
    }
    
    session.Advanced.Defer(new PatchCommandData("users/1-A", null,
        new PatchRequest
        {
            Script = @"
                var i = 0;
                for(i = 0; i < $values.length; i++)
                {
                    timeseries(id(this), $timeseries)
                    .append (
                      new Date($timeStamps[i]), 
                      $values[i], 
                      $tag);
                }",
    
            Values =
            {
                { "timeseries", "HeartRates" },
                { "timeStamps", timeStamps},
                { "values", values },
                { "tag", "watches/fitbit" }
            }
        }, null));
    
    session.SaveChanges();
  • In this sample, we remove a range of 50 time series entries from a document.

    // Delete time-series entries
    session.Advanced.Defer(new PatchCommandData("users/1-A", null,
        new PatchRequest
        {
            Script = @"timeseries(this, $timeseries)
                     .delete(
                        $from, 
                        $to
                      );",
            Values =
            {
                { "timeseries", "HeartRates" },
                { "from", baseline.AddSeconds(0) },
                { "to", baseline.AddSeconds(49) }
            }
        }, null));
    session.SaveChanges();