Is it safe to truncate pendingSegments table?

I have few questions wrt to Druid’s pendingSegments table.

  • What exactly is this table used for?
  • In case if we want to manually truncate/purge the entries in the pendingSegments table, what are the precautions that we have to be aware of?
  • Can pendingSegments table be purged when real-time indexing (Kafka) tasks are running? Or should the supervisors be suspended before manually purging the entries?


This table is used internally to allocate new segments IDs during ingestion. If a kafka or kinesis ingestion task encounters new data and doesn’t know where to put it, Druid puts it in this file temporarily, until it decides whether to write a new segment or add the data to an existing segment.
Please don’t delete this file, but you may truncate it. Anything older than a day or so is prob safe to truncate. Don’t truncate it while Kafka ingestion is running.

there’s an option to clean up old stuff automatically