Stats

A click is written twice, both times inside ctx.waitUntil, never on the response path. A failed analytics write costs a click in the stats; it never costs a redirect.

	D1 stats_daily	Analytics Engine
Holds	clicks + bots, per link, per UTC day	country, device, OS, browser, in-app, referer host, decision branch
Retention	permanent	3 rolling months
Latency	immediate	~1 minute of ingestion
Read by	GET /api/stats	Cloudflare SQL API, from a laptop

The daily counter in D1 exists because Analytics Engine only keeps three months. Without it there would be no history at all.

Permanent counts

curl -s "https://301.so/api/stats?days=7" \
  -H "Authorization: Bearer $TOKEN" -A "my-client/1.0"

Shape and parameters: API reference. Readable the instant the click lands, because it is a plain INSERT … ON CONFLICT DO UPDATE in SQLite.

Dimensions

Analytics Engine is queried through Cloudflare’s SQL API with an account-scoped token:

ACC=<account id>
curl -s "https://api.cloudflare.com/client/v4/accounts/$ACC/analytics_engine/sql" \
  -H "Authorization: Bearer $CF_TOKEN" \
  --data "SELECT blob2 AS slug, blob9 AS webview, blob11 AS outcome,
                 SUM(_sample_interval) AS clicks
            FROM clicks_301so
           WHERE timestamp > NOW() - INTERVAL '7' DAY
           GROUP BY slug, webview, outcome
           ORDER BY clicks DESC FORMAT JSON"

Column order is a contract — queries address columns by position, so new fields are only ever appended. Inserting one in the middle would rewrite the past.

Column	Contents
index1	link_id (sampling is per index)
blob1…blob5	hostname, slug, team id, country, colo
blob6…blob9	device, OS, browser, in-app browser
blob10, blob11	referer hostname, decision branch
double1	1 if bot

SUM(_sample_interval), never COUNT(*)

Analytics Engine samples by volume. _sample_interval is the weight of each retained row; counting rows undercounts silently once traffic grows.

A reading taken right after a click is not a bug

Ingestion takes about a minute. Six test clicks read back as zero, then as six. Nothing was lost — you were early.

Why the worker never reads Analytics Engine

Reading it needs an account-level Cloudflare token. Putting one inside a worker that serves public traffic would trade the entire Cloudflare account against a stats screen. So the read path stops at D1, and dimensions are read from Vincent’s machine — where the token already lives.