Support nanoseconds in tracing views

[Slach]

Currently only miliseconds is supported

But durationUnit is present in https://github.com/grafana/clickhouse-datasource?tab=readme-ov-file#with-a-configuration-file

[lunaticusgreen]

The official Grafana ClickHouse datasource plugin (latest versions for Grafana 9/10+) does support distributed trace data with nanosecond precision.

Trace support was introduced in version 2.2.0 of the plugin, including a query format for “Trace” visualization. The plugin’s configuration and query builder explicitly allow specifying the time unit for trace durations (seconds, milliseconds, microseconds, or nanoseconds).

Internally, the plugin converts nanosecond timestamps/durations to the millisecond format required by Grafana’s trace UI. You can store trace timestamps and durations in ClickHouse with nanosecond resolution, and the plugin handles them so Grafana can display the traces. However, due to Grafana and browser limitations, the UI ultimately works at millisecond resolution, so sub-millisecond differences won’t be distinguishable on the timeline. For example, it was discussed here: grafana/clickhouse-datasource#771

In summary, the plugin explicitly supports ingesting/querying trace data in nanoseconds, but the display is effectively limited to millisecond precision.