We are using the default query language for Qdrant, and we have not used anything else. Whatever Qdrant provides by default, we are using it, and we are satisfied with that. The metrics I use to evaluate the performance in indexing and retrieving vectors with Qdrant focus on response time. Response time is the primary metric. Qdrant has reduced our response time to less than one second for our 128 KB token sizes, and we are satisfied with that performance. Qdrant is open source, which means the software is free if you handle it yourself, but you need one or two engineers working on it. Since it is free, it is very good compared to other databases. I rate this review an overall 8.
