Workflow: trace sampling as a strategy

Workflow: trace sampling as a strategy

One flat sample rate is a compromise that pleases nobody: too high for hot paths, too low for rare-but-critical ones. Sample by value instead.

The principles

1. Errors are always full fidelity. Sampling applies to transactions/traces, never to error events.
2. Sample hot low-value traffic near zero: health checks, static assets, polling endpoints.
3. Sample rare high-value traffic at 1.0: checkout, payment webhooks, admin actions.
4. Keep one baseline rate (0.05-0.2) for everything else so dashboards stay representative.

Implement with the sampler

def traces_sampler(sampling_context):
    route = sampling_context.get("transaction_context", {}).get("name", "")
    if route.startswith("GET /health"): return 0.0
    if "/checkout" in route or "/webhooks/" in route: return 1.0
    return 0.1

The sampler runs per transaction, so decisions follow the request. Keep it pure and fast: no I/O, no database calls.

Mind the edges

• traces_sample_rate=0 still continues incoming distributed traces; None disables tracing entirely. Use 0, not None, on services that sit mid-trace.
• Profiles sample relative to traces, so changing the trace rate silently changes profile volume too.
• Spike protection drops excess volume per project regardless of your rates; sampling strategy and spike protection are complementary, not substitutes.

Verify

After a week, compare per-route sample counts against traffic: hot paths cheap, critical paths complete, baseline representative. Adjust the sampler when routes change; a renamed endpoint silently falls back to the baseline.

Researched against live Sentry docs 2026-09-26. The Python options page (docs.sentry.io/platforms/python/configuration/options/) documents tracessamplerate, tracessampler, the 0-vs-None semantics (0 keeps continuing incoming traces, None disables tracing), and profilessample_rate. The quotas page (docs.sentry.io/pricing/quotas/) documents per-category quotas and spike protection. The Laravel guide warns a trace rate of 1.0 burns quota fast.