m_histogram(metricName: string, [filter: bool]?) -> histogram

Selects a metric that must be an OpenTelemetry-style classic histogram (object representation) inside align. Dataset metadata, when present, must mark the metric as histogram; the shared object value column from the metric interface is read. If metadata is missing the compiler still targets histogram mode so mis-typed metrics are caught when definitions exist. Exponential histograms require m_exponential_histogram; arbitrary object metrics without that kind should use m_object; floats use m. An optional boolean filter applies after the name match. Usage outside align is rejected.

Domain

This is a scalar function (calculates a single output value for a single input row).

Categories

• Misc

Examples

align 1m, frame(back: 1m), o: histogram_combine(m_histogram("rpc_latency"))

Merges per-point classic histogram objects for the rpc_latency metric after narrowing the selection with m_histogram.