Hi everyone, We performed testing of the concurrent rewrite for knn vector queries in Lucene 9.7 and the results look great, we see up to x9 improvement on large datasets.
Our current implementation for intra-query concurrency relies on a single IndexSearcher per index which is always configured with an executor. The intention is to execute only heavy / long running queries in concurrent mode, so we use either Collector or CollectorManager API to control this behavior. But the concurrent rewrite in KnnVectorQuery is effectively always enabled if the IndexSearcher is configured with an executor, so we need to find another way to turn it on and off when needed. Knowing that IndexSearcher#search(Query, Collector) is going to be removed <https://issues.apache.org/jira/browse/LUCENE-10002> eventually, and a similar change <https://github.com/apache/lucene/pull/632> was implemented for DrillSideays, my understanding is that the long-term plan is to rely only on the presence of the executor in IndexSearcher to select the sequential/concurrent code path. Is this correct, or would people be open to introducing an additional flag (e.g. in IndexSearch#search) to be able to override the default behavior? -- Regards, Alex
