By the end of this chapter you will be able to:

You will also learn how to pass only some records to the receiving stream using the Maximum Number of Records per Group option.

In this exercise you will select the most recent sales record for each customer from the set of combined updates you created in the previous exercise.

Create an aggregate stream

In PhixFlow, we use an aggregate stream to show that we are rearranging data from a single stream. See the reference page Aggregating Data for details.

1. From the model toolbar, drag  Aggregate Table into the model.
2. Set the stream Name to Latest Package Update.
3. Add a pipe from Combined Updates:
   1. Hover your mouse pointer over the stream Combined Updates.
   2. In the context toolbar, click  Connector.
   3. Click the stream Latest Package Update to connect the pipe.
   4. PhixFlow opens the pipe settings. Click  OK to close the settings.
4. Drag all attributes from Combined Updates to Latest Package Update.
   1. Make sure the open settings form is for the stream Latest Package Update.
   2. Hover your mouse pointer over the stream Combined Updates.
   3. In the context toolbar, click Attributes. Phixflow lists the data attributes (column titles) for this stream.
   4. Select all the attributes and drag them into the Latest Package Update settings → Attributes section.
      
   5. Click  OK to save and close the Latest Package Updates settings.
   6. Close the attributes popup window.
5. In the Channel Package model toolbar, click  Save.

When you next run this model, the Latest Package Updates stream will pull in all the data from the Combined Updates stream. At the moment the data will come into the aggregate stream in any order. In PhixFlow you can sort the data as it comes through the input pipe to the aggregate stream. You can also choose to add specific records to the receiving stream.

Group and order data on an input pipe

In PhixFlow, as data records are passed through the model, you can rearrange the records or select records that meet certain criteria. You can do this using options on the stream or options on the pipe. In this section you will use options on the pipe to pass one record per customer to the receiving stream. That record will be the most recent one for the customer. To achieve this you will:

• group the data, so that all the records with the same Customer Ref number are grouped into adjacent rows in the table.
• sort the data from the newest to the oldest Sales Date. This means that the first record delivered by the input pipe, for each Customer Ref, is the most recent for that customer.
• pass only the first record per customer record to the receiving stream.

1. In the model, double-click on the pipe from the  Combined Updates stream.
2. Expand the Sort/Group section toolbar.
3. In the section toolbar, click Attributes. Phixflow opens a list of the attributes that the Combined Updates stream can pass to the pipe.
   
4. Drag in CustomerRef. By default, this attribute has Group ticked and Direction set to A-Z (ascending).
   This means the data records will be grouped by CustomerRef.
5. Drag in SalesDate. Double-click on SalesDate in the Sort/Group grid. PhixFlow opens the settings for the attribute. In Basic Settings, set:
   • Direction: Z-A (descending)
     
   • Group:  Untick
   • Click  OK to save the change and close the attribute settings.
     This means the data records will be sorted by date, with the most recent first. 
6. In the pipe settings → Sort/Group section, set Maximum Number of Records per Group to 1.
   This means PhixFlow will pass only one record, the first and therefore most recent, to the receiving stream.
   
   
7. Click  Save to save the pipe settings, which should look like this:
   
8. In the model toolbar, click  Save to save the model.

Now you can run the model and view the stream data.

1. Hover your mouse pointer over the Latest Package Update stream and click  Run Analysis then click YES to confirm.
2. When PhixFlow notifies you that the analysis is finished, hover your mouse pointer over the Latest Package Update stream again.
3. Click  Show view.
4. In the drop-down list, select  Default View.  PhixFlow displays the data.
   
   Notice that there is only one record per customer reference.
5. If you also look at the default view for the Combined Updates stream, you will see that some customers, such as C056 have more than one record. The most recent record has been passed to the Latest package Update stream.