Is your feature request related to a problem?
Certain PPL operators naturally require data-driven (dynamic) columns whose names and counts are not known at plan time. It is the blocker to support timechart and spath command

Example — timechart pivot

source=logs
| timechart span=1h count() by status limit=3

Problem: The set of status labels (e.g., ERROR, OK, TIMEOUT) is only known at runtime and can vary by dataset. Producing a wide, pivoted table requires dynamic columns, which are not available under a fixed per-operator schema.

Example — spath with object keys

source=idx
| spath input=doc path=event.tags

Problem: event.tags is a JSON object whose keys differ across documents. The extracted keys are unknown until read, so the output columns are inherently dynamic.