Client Count Daily Reference

This document is a work in progress. The work is being tracked here.

Introduction

The client_count_daily dataset is useful for estimating user counts over a few pre-defined dimensions.

The client_count_daily dataset is similar to the deprecated client_count dataset except that is aggregated by submission date and not activity date.

Content

This dataset includes columns for a dozen factors and an HLL variable. The hll column contains a HyperLogLog variable, which is an approximation to the exact count. The factor columns include submission date and the dimensions listed here. Each row represents one combinations of the factor columns.

Background and Caveats

It's important to understand that the hll column is not a standard count. The hll variable avoids double-counting users when aggregating over multiple days. The HyperLogLog variable is a far more efficient way to count distinct elements of a set, but comes with some complexity. To find the cardinality of an HLL use cardinality(cast(hll AS HLL)). To find the union of two HLL's over different dates, use merge(cast(hll AS HLL)). The Firefox ER Reporting Query is a good example to review. Finally, Roberto has a relevant write-up here.

Accessing the Data

The data is available in Re:dash. Take a look at this example query.

I don't recommend accessing this data from ATMO.

Further Reading

Data Reference

Example Queries

Compute DAU for non-windows clients for the last week

WITH sample AS (
  SELECT
    os,
    submission_date,
    cardinality(merge(cast(hll AS HLL))) AS count
  FROM client_count_daily
  WHERE submission_date >= DATE_FORMAT(CURRENT_DATE - INTERVAL '7' DAY, '%Y%m%d')
  GROUP BY
    submission_date,
    os
)

SELECT
  os,
  -- formatting date as late as possible improves performance dramatically
  date_parse(submission_date, '%Y%m%d') AS submission_date,
  count
FROM sample
WHERE
  count > 10 -- remove outliers
  AND lower(os) NOT LIKE '%windows%'
ORDER BY
  os,
  submission_date DESC

Compute WAU by Channel for the last week

WITH dau AS (
  SELECT
    normalized_channel,
    submission_date,
    merge(cast(hll AS HLL)) AS hll
  FROM client_count_daily
  -- 2 days of lag, 7 days of results, and 6 days preceding for WAU
  WHERE submission_date > DATE_FORMAT(CURRENT_DATE - INTERVAL '15' DAY, '%Y%m%d')
  GROUP BY
    submission_date,
    normalized_channel
),
wau AS (
  SELECT
    normalized_channel,
    submission_date,
    cardinality(merge(hll) OVER (
      PARTITION BY normalized_channel
      ORDER BY submission_date
      ROWS BETWEEN 6 PRECEDING AND 0 FOLLOWING
    )) AS count
  FROM dau
)

SELECT
  normalized_channel,
  -- formatting date as late as possible improves performance dramatically
  date_parse(submission_date, '%Y%m%d') AS submission_date,
  count
FROM wau
WHERE
  count > 10 -- remove outliers
  AND submission_date > DATE_FORMAT(CURRENT_DATE - INTERVAL '9' DAY, '%Y%m%d') -- only days that have a full WAU

Caveats

The hll column does not product an exact count. hll stands for HyperLogLog, a sophisticated algorithm that allows for the counting of extremely high numbers of items, sacrificing a small amount of accuracy in exchange for using much less memory than a simple counting structure.

When count is calculated over a column that may change over time, such as total_uri_count_threshold, then a client would be counted in every group where they appear. Over longer windows, like MAU, this is more likely to occur.

Scheduling

This dataset is updated daily via the telemetry-airflow infrastructure. The job runs as part of the main_summary DAG.

Schema

The data is partitioned by submission_date which is formatted as %Y%m%d, like 20180130.

As of 2018-03-15, the current version of the client_count_daily dataset is v2, and has a schema as follows:

root
 |-- app_name: string (nullable = true)
 |-- app_version: string (nullable = true)
 |-- country: string (nullable = true)
 |-- devtools_toolbox_opened: boolean (nullable = true)
 |-- e10s_enabled: boolean (nullable = true)
 |-- hll: binary (nullable = true)
 |-- locale: string (nullable = true)
 |-- normalized_channel: string (nullable = true)
 |-- os: string (nullable = true)
 |-- os_version: string (nullable = true)
 |-- top_distribution_id: string (nullable = true)
 |-- total_uri_count_threshold: integer (nullable = true)

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