PCDOE Implementing service monitoring strategies Practice Question

Exhibit

```
fetch cloud_run_revision::https://googleapis.com/traces/span
| filter spans == "my-service"
| align delta(1m)
| every 1m
| group_by [span_id], [latency: percentile(99)]
```

The above MQL query is used in a Cloud Monitoring dashboard. What does it display?

⚠ Common exam trap

Google Cloud often tests the distinction between aggregating across all spans (e.g., service-level percentile) versus grouping by a dimension like `span_id`, leading candidates to mistakenly choose a service-wide aggregation when the query explicitly groups by a finer granularity.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The 99th percentile latency of each span_id, every minute.

The MQL query uses the `fetch` command to retrieve spans from the `my-service` service, then applies `percentile(99)` to the latency metric, and groups the result by `span_id` using the `into` clause. The `every 1m` parameter sets the alignment window to one minute. This produces a time series showing the 99th percentile latency for each distinct span_id, updated every minute.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The total number of spans in 'my-service' each minute.
Why it's wrong here
The query uses percentile(99) on latency, not counting spans.
✗
The maximum latency of spans grouped by span_id.
Why it's wrong here
The query uses percentile(99), not max.
✗
The 99th percentile latency of all spans in the 'my-service' service, every minute.
Why it's wrong here
The group_by [span_id] breaks down per span_id, not aggregated per service.
✓
The 99th percentile latency of each span_id, every minute.
Why this is correct
The group_by [span_id] combined with percentile(99) on latency gives per-span_id 99th percentile values.

Go deeper

PCDOE Implementing service monitoring strategies Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

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