Error Handling and Debugging Interview Questions | Qdrant | NextRound

1What's your recovery plan if an entire Qdrant cluster is lost (e.g., all nodes' disks fail) and you only have periodic snapshots?Advanced

2What symptoms would indicate a 'split-brain' style problem in a distributed Qdrant cluster, and how does the Raft-based consensus layer prevent it?Advanced

3A filter query that should return results returns an empty list. What would you check first?Beginner

4A client gets a dimension-mismatch error when inserting a point. What are the most common root causes?Beginner

5Why might a collection created without specifying a distance metric or vector size fail immediately, and what does that tell you about how Qdrant treats collection configuration?Beginner

6What causes a 'collection not found' error immediately after a collection was reportedly created successfully in a distributed cluster?Advanced

7Search results seem semantically wrong even though the embedding model is known to work well. What layers would you check to isolate the problem?Advanced

8Recall dropped noticeably after enabling quantization. How would you determine whether the quantization configuration or the rescoring settings are the cause?Advanced

9A previously fast query has become slow after months of continuous upserts and deletes, with no configuration changes. What's the most likely explanation?Advanced

10How would you distinguish a latency problem caused by disk I/O from one caused by CPU-bound distance computation?Advanced

11One node in a three-node Qdrant cluster crashes. What happens to reads and writes for shards that had a replica on that node?Advanced

12After a crashed node recovers and rejoins the cluster, how does it catch up on writes it missed?Advanced