bigquery

Original：🇺🇸 English

Translated

Query Mozilla telemetry data directly from BigQuery using the bq CLI. Use when the user wants to run SQL against Firefox telemetry, analyze Windows version distribution, count DAU/MAU/WAU, query Glean metrics, or investigate user populations. Triggers on "bigquery", "bq", "telemetry query", "DAU", "MAU", "Windows distribution", "macOS distribution", "Darwin version", "Linux distribution", "kernel version", "client count", "user count", "Glean metrics query", "baseline_clients".

1installs

Sourcejwmossmoz/agent-skills

Added on2026-02-18

NPX Install

npx skill4agent add jwmossmoz/agent-skills bigquery

SKILL.md Content

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BigQuery

Query Mozilla telemetry data directly using the

bq

CLI.

Prerequisites

```
gcloud
```
and
```
bq
```
CLI installed (
```
brew install google-cloud-sdk
```
)
Authenticated:
```
gcloud auth login
```
with a Mozilla account
Billing project set: queries run against a project you have
```
bigquery.jobs.create
```
on
(Optional but highly recommended) mozdata-claude-plugin — provides Glean Dictionary MCP for metric/ping discovery, making it much easier to find the right tables and columns

Authentication

bash

# Check current account
gcloud config get-value account

# Re-authenticate if needed
gcloud auth login

# List available projects
gcloud projects list --format="table(projectId,name)"

# Set billing project (mozdata is the standard choice)
gcloud config set project mozdata

If queries fail with "Access Denied", the billing project likely lacks permissions. Try

--project_id=mozdata

.

Running Queries

bash

# Basic query
bq query --project_id=mozdata --use_legacy_sql=false --format=pretty "SELECT ..."

# Dry run (check cost before executing)
bq query --project_id=mozdata --use_legacy_sql=false --dry_run "SELECT ..."

Always use

--project_id=mozdata

and

--use_legacy_sql=false

.

Table Selection

Choose the right table — this is the most important optimization:

Query Type	Table	Why
Windows version distribution	`telemetry.windows_10_aggregate`	Pre-aggregated, instant
DAU/MAU by standard dimensions	`firefox_desktop_derived.active_users_aggregates_v3`	Pre-computed, 100x faster
DAU with custom dimensions	`firefox_desktop.baseline_clients_daily`	One row per client per day
MAU/WAU/retention	`firefox_desktop.baseline_clients_last_seen`	Bit patterns, scan 1 day not 28
Event analysis	`firefox_desktop.events_stream`	Pre-unnested, clustered
Mobile search	`search.mobile_search_clients_daily_v2`	Pre-aggregated
Specific Glean metric	`firefox_desktop.metrics`	Raw metrics ping

All tables are in the

moz-fx-data-shared-prod

project. Fully qualify as

`moz-fx-data-shared-prod.{dataset}.{table}`

.

Critical Rules

Always use aggregate tables first — raw tables are 10-100x more expensive

Always include partition filter —

submission_date

or

DATE(submission_timestamp)

Use
sample_id = 0
for development (1% sample) — remove for production
Say "clients" not "users" — BigQuery tracks
```
client_id
```
, not actual humans
Never join across products by client_id — each product has its own namespace
Use
events_stream
for events — never raw
```
events_v1
```
(requires UNNEST)
Use
baseline_clients_last_seen
for MAU — bit patterns, scan 1 day not 28

References

```
references/tables.md
```
— Detailed table schemas and common query patterns
```
references/os-versions.md
```
— Windows, macOS, and Linux version distribution queries with build number, Darwin, and kernel version mappings

Related Skills

redash — Web UI frontend to BigQuery with visualizations and sharing
mozdata:query-writing — Guided query writing with Glean Dictionary MCP
mozdata:probe-discovery — Find Glean metrics and telemetry probes