How to: Flamegraph query example:
```sql
SELECT length(trace)  - level_num AS level, label, count() AS value, 0 self
FROM system.trace_log
  ARRAY JOIN arrayEnumerate(trace) AS level_num,
  arrayMap(x -> if(addressToSymbol(x) != '', demangle(addressToSymbol(x)), 'unknown') , trace) AS label
WHERE trace_type='Real' AND $timeFilter
GROUP BY level, label, trace
ORDER BY trace, level
```