Function durationBucketSeries

telemetry-dashboard/src/api.ts:414–457

"Session run length over time": one series per duration bucket, bucket-ordered.

(env: Env, range: Range)

/** "Session run length over time": one series per duration bucket, bucket-ordered. */
async function durationBucketSeries(env: Env, range: Range): Promise<ApiResult> {
  const { results } = await env.DB.prepare(
    `SELECT day, value, sum(count) AS n
       FROM daily_dim_counts
      WHERE dim = 'duration_bucket' AND event = 'index' AND day BETWEEN ? AND ?
      GROUP BY day, value`,
  )
    .bind(range.from, range.to)
    .all<{ day: string; value: string; n: number }>();

  const labels = dayList(range);
  const perBucket = new Map<string, Map<string, number>>();
  for (const row of results) {
    let series = perBucket.get(row.value);
    if (!series) perBucket.set(row.value, (series = new Map()));
    series.set(row.day, row.n ?? 0);
  }

  // Fixed buckets first and always present (a bucket with no runs is a real zero,
  // and dropping it would silently renumber the ordinal colour ramp); anything
  // unexpected from an older client is appended rather than hidden.
  const extra = [...perBucket.keys()].filter((v) => !DURATION_BUCKETS.includes(v as never)).sort();
  const order = [...DURATION_BUCKETS, ...extra];

  const datasets = order.map((bucket) => ({
    label: bucket,
    data: densify(labels, perBucket.get(bucket) ?? new Map()),
  }));

  return {
    body: {
      range,
      metric: 'duration_buckets',
      title: 'Indexing run length over time',
      labels,
      datasets,
      rows: labels.map((day, i) => ({
        day,
        ...Object.fromEntries(datasets.map((d) => [d.label, d.data[i] ?? 0])),
      })),
    },
    cacheControl: CACHE_CONTROL,
  };
}

// ---------------------------------------------------------------------------
// /api/breakdown — the bars and pies