Bug 1632635 - Make Amplitude properties top-level (#968)

* Add top-level Amplitude user props

* Don't send empty array user props

* Correct schema mismatch on union

sql/firefox_accounts/fxa_amplitude_export/view.sql

@@ -34,7 +34,11 @@ active_events AS (
     'fxa_activity - active' AS event_type,
     timestamp,
     TO_JSON_STRING(STRUCT(services, oauth_client_ids)) AS event_properties,
-    '' AS user_events
+    region,
+    country,
+    `LANGUAGE`,
+    app_version AS version,
+    '' AS user_properties
   FROM
     active_users
 ),
@@ -46,6 +50,11 @@ user_properties AS (
     '$identify' AS event_type,
     timestamp,
     '' AS event_properties,
+    -- Some Amplitude properties are top level
+    region,
+    country,
+    `LANGUAGE`,
+    app_version AS version,
     -- We don't want to include user_properties if they are null, so we need
     -- to list them out explicitly and filter with WHERE
     CONCAT(
@@ -56,18 +65,6 @@ user_properties AS (
             CONCAT(TO_JSON_STRING(key), ":", value)
           FROM
             (
-              SELECT AS STRUCT
-                "region" AS key,
-                TO_JSON_STRING(region) AS value,
-              UNION ALL
-              SELECT AS STRUCT
-                "country" AS key,
-                TO_JSON_STRING(country) AS value,
-              UNION ALL
-              SELECT AS STRUCT
-                "LANGUAGE" AS key,
-                TO_JSON_STRING(LANGUAGE) AS value,
-              UNION ALL
               SELECT AS STRUCT
                 "os_used_day" AS key,
                 TO_JSON_STRING(os_used_day) AS value,
@@ -104,21 +101,18 @@ user_properties AS (
                 "ua_browser" AS key,
                 TO_JSON_STRING(ua_browser) AS value,
               UNION ALL
-              SELECT AS STRUCT
-                "app_version" AS key,
-                TO_JSON_STRING(app_version) AS value,
-              UNION ALL
               SELECT AS STRUCT
                 "$postInsert",
                 TO_JSON_STRING(STRUCT(fxa_services_used)) AS value
             )
           WHERE
             value != "null"
+            AND value != "[]"
         ),
         ","
       ),
       "}"
-    ) AS used_properties
+    ) AS user_properties
   FROM
     active_users
 ),