detect-n-plus-one

Testing & Quality

Detect N+1 query patterns in a trace, where one parent operation triggers many near-identical child spans (often database calls). Use when a trace is slow and shows repeated downstream calls, or when the user asks about N+1, repeated queries, or chatty DB access.

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Source SKILL.md: https://github.com/jaegertracing/jaeger/blob/HEAD/cmd/jaeger/internal/extension/jaegerquery/internal/mcptools/skills/detect-n-plus-one/SKILL.md

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Detect N+1 Query Patterns

When this applies

A parent span has many child spans with the same operation name and similar duration, typically database queries or RPC calls.

Procedure

Find candidate traces with search_traces.
Pull the span tree with get_trace_topology; group child spans by operation name under each parent.
Flag any group with more than 10 near-identical siblings as a potential N+1 pattern. Check that children have similar durations (within 2x of the median).
Inspect repeated siblings with get_span_details to confirm they target the same downstream service and carry similar attributes.
Report: the parent span (service, operation), the repeated child operation, the count, total wall-clock time consumed, and whether children run sequentially or in parallel.

Gotchas

Parallel fan-out can look like N+1 but is intentional — check whether children overlap in time before flagging.
Batch operations may share an operation name but carry different payloads — check span attributes to distinguish.