Define each metric once

How to do it

Write the definition as code or SQL with a name, owner, formula, filters and time zone. A semantic layer such as dbt's MetricFlow or Cube does this, or a folder of reviewed SQL views. "Active user" must mean the same in every chart, for example "signed in at least once in the last 28 days". Change a definition through review, and note the change date on charts.

Example

CREATE VIEW metric_weekly_active_users AS
SELECT date_trunc('week', received_at AT TIME ZONE 'UTC') AS week,
       count(DISTINCT anonymous_id) AS weekly_active_users
FROM events
WHERE name = 'session_started' AND traffic = 'visitor'
GROUP BY 1;

export const METRICS = {
  weekly_active_users: { owner: 'product', view: 'metric_weekly_active_users', definition: 'Distinct analytics IDs with session_started in an ISO week, UTC' },
};

METRICS = {
    "weekly_active_users": {"owner": "product", "view": "metric_weekly_active_users",
                            "definition": "Distinct analytics IDs with session_started in an ISO week, UTC"},
}

How to check

A script lists every saved dashboard query and fails on any that computes a named metric without the shared view or metric. Two dashboards showing the same metric for the same day show the same number.