84 lines
2.3 KiB
Markdown
84 lines
2.3 KiB
Markdown
# Analytics Engine Patterns
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## Use Cases
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| Use Case | Key Metrics | Index On |
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|----------|-------------|----------|
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| API Metering | requests, bytes, compute_units | api_key |
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| Feature Usage | feature, action, duration | user_id |
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| Error Tracking | error_type, endpoint, count | customer_id |
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| Performance | latency_ms, cache_status | endpoint |
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| A/B Testing | variant, conversions | user_id |
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## API Metering (Billing)
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```typescript
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env.ANALYTICS.writeDataPoint({
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blobs: [pathname, method, status, tier],
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doubles: [1, computeUnits, bytes, latencyMs],
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indexes: [apiKey]
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});
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// Query: Monthly usage by customer
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// SELECT index1 AS api_key, SUM(double2) AS compute_units
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// FROM usage WHERE timestamp >= DATE_TRUNC('month', NOW()) GROUP BY index1
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```
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## Error Tracking
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```typescript
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env.ANALYTICS.writeDataPoint({
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blobs: [endpoint, method, errorName, errorMessage.slice(0, 1000)],
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doubles: [1, timeToErrorMs],
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indexes: [customerId]
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});
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```
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## Performance Monitoring
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```typescript
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env.ANALYTICS.writeDataPoint({
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blobs: [pathname, method, cacheStatus, status],
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doubles: [latencyMs, 1],
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indexes: [userId]
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});
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// Query: P95 latency by endpoint
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// SELECT blob1, quantile(0.95)(double1) AS p95_ms FROM perf GROUP BY blob1
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```
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## Anti-Patterns
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| ❌ Wrong | ✅ Correct |
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|----------|-----------|
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| `await writeDataPoint()` | `writeDataPoint()` (fire-and-forget) |
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| `indexes: [method]` (low cardinality) | `blobs: [method]`, `indexes: [userId]` |
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| `blobs: [JSON.stringify(obj)]` | Store ID in blob, full object in D1/KV |
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| Write every request at 10M/min | Pre-aggregate per second |
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| Query from Worker | Query from external service/API |
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## Best Practices
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1. **Design schema upfront** - Document blob/double/index assignments
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2. **Always include count metric** - `doubles: [latency, 1]` for AVG calculations
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3. **Use enums for blobs** - Consistent values like `Status.SUCCESS`
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4. **Handle sampling** - Use ratios (avg_latency = SUM(latency)/SUM(count))
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5. **Test queries early** - Validate schema before heavy writes
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## Schema Template
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```typescript
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/**
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* Dataset: my_metrics
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*
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* Blobs:
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* blob1: endpoint, blob2: method, blob3: status
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*
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* Doubles:
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* double1: latency_ms, double2: count (always 1)
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*
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* Indexes:
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* index1: customer_id (high cardinality)
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*/
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```
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