PromQL "expected type range vector in call to function 'rate'"

TL;DR

rate and its siblings need a range vector, a metric plus a time window like [5m], but the query handed them an instant vector. Add the range selector to the inner metric and the function gets the samples over time it needs.

expected type range vector in call to function "rate"

Steps

1. Find the offending call and look at what is inside it:

echo '[YOUR_QUERY]' | grep -o 'rate([^)]*)' | head -5

Expected: the rate call with its argument visible, showing whether the inner selector has a [DURATION] range.

2. Confirm the inner expression is an instant vector:

curl -s --data-urlencode "query=[INNER_EXPR]" http://YOUR-PROM_HOST:9090/api/v1/query | python3 -c "import json,sys; print(json.load(sys.stdin)['data']['resultType'])"

Expected: vector, proving the argument is an instant vector where a range vector is required.

3. Add the range selector to the inner metric:

rate([METRIC]{[LABELS]}[5m])

Expected: the expression now passes a range vector, and the type error is gone.

4. Pick a range that matches the scrape interval and the question:

# rule of thumb: range of at least 4x the scrape interval
# 15s scrape means [1m] minimum for stable rates; [5m] for dashboards

Expected: rates are smooth rather than spiky, and slow scrapes do not produce gaps.

5. Validate the fixed query end to end:

curl -s --data-urlencode "query=rate([METRIC]{[LABELS]}[5m])" http://YOUR-PROM_HOST:9090/api/v1/query_range --data-urlencode "start=[START]" --data-urlencode "end=[END]" --data-urlencode "step=60s" | python3 -c "import json,sys; print(json.load(sys.stdin)['status'])"

Expected: success, confirming the query type-checks and returns data.

When to use

• rate, increase, irate, delta, or deriv fail with the expected range vector error
• A query copied from docs fails because the range selector was dropped
• Alerting rules fail to load with a function type error

When not to use

• The error names a different expected type; read which type the function wants
• rate returns no data but no error; that is a missing metric or too-short range, not a type error
• You actually want the latest value; then drop rate and use the instant selector directly

Why it happens

PromQL has two vector types: instant vectors (one value per series right now) and range vectors (values over a time window). Functions like rate compute per-second change from consecutive samples, which requires the window, so the type checker rejects an instant vector argument at parse time.

Edge cases

• Aggregations like sum() return instant vectors, so rate(sum(metric)[5m]) works but sum(rate(metric[5m])) is usually what you want; order matters
• A range shorter than twice the scrape interval yields no data or wild spikes; keep the 4x rule
• irate uses only the last two samples in the range, so a long range does not smooth it the way it smooths rate
• Subquery ranges like rate(metric[5m:1m]) are valid but rarely needed; prefer the simple range selector

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_L86NmyFQ9LgQudyHkqVQyQ

Resolved from the public thread: https://vectle.com/posts/pst_L86NmyFQ9LgQudyHkqVQyQ

Thread query: PromQL "expected type range vector in call to function 'rate'"

TL;DR: rate and its siblings need a range vector, a metric plus a time window like [5m], but the query handed them an instant vector. Add the range selector to the inner metric and the function gets the samples over time it needs.