Before doing an analysis, it is important to know which products you want to include. Here is a quick overview of Mozilla's mobile products.

Firefox Lite was formerly known as Rocket. It is only available in certain countries in Asia Pacific - for more information on Firefox Lite data please see the telemetry documentation.

Focus is our privacy focused mobile browser which blocks trackers by default and does not store a browsing history.

Klar is the release name for Focus in Germany.

For more information on how telemetry is sent for iOS apps, see the telemetry documentation.

Some telemetry is also sent by FirefoxReality and some non-Mozilla forks of our browsers. It is best to filter on metadata_app_name to ensure you are looking at only the app you are trying to analyze data for.

Mobile data is structured differently than desktop. Instead of sending a main ping, mobile has two key types of pings - a core ping and an events ping. The core ping is sent once per session and contains a much smaller set of metrics than the main ping, due to network and data size constraints. All mobile apps send the core ping. For more information on the core ping, there is telemetry documentation here.

Event pings are not sent for all products. Event pings are sent by Focus Android, Focus iOS, Klar, Firefox for FireTV, Firefox for Echo Show and Firefox Lite. Event pings are sent more often than core pings, at most once per 10 minute interval. If the ping records 10,000 events it is sent immediately, unless it is within 10 minutes of the last event ping sent, in which case some data may be lost. For more information on the event ping, there is telemetry documentation here.

Fennec (Firefox Android) does not send event pings, but instead has a saved_session ping which has the same format as main_summary but is only available for pre-release users and select few release users who have opted in to telemetry collection. Data from this must be treated with caution as it comes from a biased population and should not be used to make conclusions about Fennec users as a whole.

For more information on the implementation of the event pings and to view event descriptions for Focus, Firefox for FireTV or Firefox for Echo Show please see the linked documentation.

For most analyses of mobile data, use the telemetry_core_parquet table. This table contains data for all the non-desktop Firefox applications which send core pings.

Unlike main summary, you can query telemetry_core_parquet directly. Remember to filter on app_name and os, as Firefox iOS and Firefox Android have the same app_name. Best practice is to always filter on app_name, os, app version (found as metadata_app_version) and release channel (which can be found as under metadata as metadata.normalized_channel).

There are versioned tables for telemtry_core_parquet but the table without a _v# suffix is the most up to date table and it is best to use this in your analysis.

The metadata field contains a list of useful metrics. To access you can query metadata.metric_name for the metric_name of your choice. Metrics included in metadata are: [document_id, timestamp, date, geo_country, geo_city, app_build_id, normalized_channel] as described here.

The seq field indicates the order of the pings coming in. seq = 1 is the first ping we have received for that client id and can be used to proxy new users.

Mobile has a core_client_count table which has a created date and unique client id for each new install. This does not fully replicate what client_count_daily does for Desktop but can be useful for some analyses.

For other core ping derived tables see the documentation here. These (with the exception of mobile_clients) are derived from the saved_session ping only available as an opt-in on Fennec release, so should be used with caution.

There are multiple event tables for mobile data. The two main event tables are telemetry_mobile_event_parquet and telemetry_focus_event_parquet. As the name suggests, the event pings from Focus (iOS, Android and Klar) get sent to telemetry_focus_event_parquet and the other apps send data to telemetry_mobile_event_parquet. Both tables have the same format and columns.

This table contains event data for Firefox for Fire TV, Firefox for Echo Show and Firefox Lite. There is a metadata column containing a list of metrics including [].

Like when querying telemetry_core_parquet there are multiple apps contained in each table, so it is best practice to filter on at leaseapp_name and os. One thing to note is that there is no app_version field in these tables, so in order to filter or join on a specific version you must know the corresponding metadata.app_build_id(s) for that app_version. This can be found by reaching out to the engineering team building the app.

Some other applications also send event data to this table, including Lockbox and FirefoxReality. For more information on the event data sent from these applications, see their documentation.

This table contains event data for Focus Android, Focus iOS and Klar.

Like when querying telemetry_core_parquet there are multiple apps contained in each table, so it is best practice to filter on at leaseapp_name and os. One thing to note is that there is no app_version field in these tables, so in order to filter or join on a specific version you must know the corresponding app_build_id(s) for that app_version. This can be found by reaching out to the engineering team building the app.

Some other applications send data to this table but it is preferred to use this only for analysis of event data from Focus and it's related apps.

Each app has it's own set of release channels and each app implements them in it's own way. Most have a nightly, beta, release and an other channel, used at various stages of development. Users sign up to test pre-released versions of the app. In Focus Android, the beta channel uses the same APK in the Google Play Store as the release channel, but beta users get access to this version earlier than the release population. Once the release version is published, Beta users will be on the same version of the app as Release users and will be indistinguishable (without a query going back and flagging them by client_id). Beta releases have their normalized_channel tagged release and the only way to filter to beta users is to check that they were on a higher version number before the official release date.

There was an incident on Oct 25, 2018 where a chunk of client_ids on Firefox Android were reset to the same client_id. For more information see the blameless post-mortem document here or bug. Because of this, some retention analyses spanning this time frame may be impacted.

In future, Android apps will use Glean - the new mobile telemetry SDK. Plans are to integrate this new SDK starting with Project Fenix, then update the other existing apps to Glean starting the second half of 2019. Instead of core and event pings, Glean will send baseline, metrics and events pings. For more information on Glean visit their GitHub page or #Glean on Slack.