How does efConstruction have an impact on search time for IVFHNSW (as mentioned in this description)? I am observing something in my experiments but can’t figure out why.
efConstruction primarily effects your build time (eg larger efConstruction == longer build time). It has been some time since working with HNSW so take this with a pinch of salt, different efConstruction values create a more or less optimized graph, so search times could be slower or faster because of that.
Generally, greater efConstruction means more optimized graph, and faster search times. But I don’t think there is a perfect correlation.
regarding the efConstruction parameter, I have a question about the performance graphs shown in the HNSW section. How can M be greater than efConstruction ? In my understanding of the paper algorithms 1 and 2 by Malkov and Yashumin, during the node insertion, the edges are created between the inserted node and the M (or Mmax) nearest neighbors among the efConstruction ones returned for a given layer… So it seems to me that M is always less or equal to efConstruction. Same for the efSearch parameter which is by construction less or equal to the efConstruction, the maximum possible value for M (Mmax).
Thanks for your clarification