fix(): usage reporting first seen duplicates

sql_generators/usage_reporting/templates/usage_reporting_clients_first_seen_v1.query.sql.jinja

@@ -10,26 +10,26 @@ WITH
       @submission_date AS first_seen_date,
       {% endif %}
       {% endraw %}
-      app_channel,
+      IFNULL(app_channel, "") AS app_channel,
     FROM
       `{{ project_id }}.{{ channel_dataset }}.usage_reporting_clients_daily`
     WHERE
       usage_profile_id IS NOT NULL
-      {% raw %}
-      {% if is_init() %}
+    {% raw %}
+    {% if is_init() %}
       AND submission_date > "2014-10-10"
-      {% else %}
-      AND submission_date = @submission_date
-      {% endif %}
-      {% endraw %}
     GROUP BY
       usage_profile_id,
       app_channel
+    {% else %}
+      AND submission_date = @submission_date
+    {% endif %}
+    {% endraw %}
   ),
 _previous AS (
   SELECT
     usage_profile_id,
-    app_channel,
+    IFNULL(app_channel, "") AS app_channel,
   FROM
     `{{ project_id }}.{{ channel_dataset }}_derived.{{ view_name }}_v1`
   WHERE
@@ -45,7 +45,7 @@ _previous AS (
 SELECT
   first_seen_date,
   usage_profile_id,
-  app_channel,
+  NULLIF(app_channel, "") AS app_channel,
 FROM
   _current
 LEFT JOIN

sql_generators/usage_reporting/templates/usage_reporting_clients_first_seen_v1.schema.yaml.jinja

@@ -16,4 +16,4 @@ fields:
   name: app_channel
   type: STRING
   description: |
-    The channel the application is being distributed on.
+    The channel the application is being distributed on, on mobile this is expected to be mostly null.

sql_generators/usage_reporting/templates/usage_reporting_clients_last_seen_v1.query.sql.jinja

@@ -4,7 +4,7 @@
 WITH _current AS (
   SELECT
     usage_profile_id,
-    app_channel,
+    IFNULL(app_channel, "") AS app_channel,
     -- The rightmost bit in 'days_since_seen' represents whether the user sent a usage_reporting ping on the submission_date.
     CAST(TRUE AS INT64) AS days_seen_bits,
     -- The rightmost bit in days_active_bits represents whether the user counts as active on the submission_date.
@@ -20,7 +20,7 @@ WITH _current AS (
 _previous AS (
   SELECT
     usage_profile_id,
-    app_channel,
+    IFNULL(app_channel, "") AS app_channel,
     days_seen_bits,
     days_active_bits,
     days_created_profile_bits,
@@ -45,10 +45,11 @@ SELECT
     udf.combine_adjacent_days_28_bits(
       _previous.days_created_profile_bits,
       _current.days_created_profile_bits
-    ) AS days_created_profile_bits
+    ) AS days_created_profile_bits,
+    NULLIF(app_channel, "") AS app_channel
   )
 FROM
   _current
 FULL JOIN
   _previous
-  USING (usage_profile_id)
+  USING (usage_profile_id, app_channel)