Can VectorDBBench be configured to set the number of concurrent operations for inserting data into Elasticsearch?

When we were conducting the regular VectorDBBench test to evaluate the performance of Elasticsearch, we found that the insert efficiency of Elasticsearch was extremely slow. We speculate that this is because VectorDBBench did not perform concurrent insertions when importing data. In reality, Elasticsearch in production applications supports multiple concurrent insertions. The insert performance test results here do not match the expectations. Can VectorDBBench set the number of concurrent insertions for Elasticsearch?

Start by tracing VectorDBBench's Elasticsearch data-import path and checking whether it already exposes concurrency settings for other backends. Run the regular Elasticsearch benchmark to establish the current insertion behavior; done means the benchmark can configure concurrent insertions and reports the resulting performance clearly.