jimczi opened a new pull request, #14076: URL: https://github.com/apache/lucene/pull/14076
This change reverts #13985 and makes sure each knn format sticks to a single read advice consistently. Switching read advice during merges might help some use cases, but it can also hurt others—e.g. when search and merges are running at the same time. To balance this, the approach here picks one read advice per format, focusing on what’s most resource-intensive for that format. For formats using HNSW, the read advice is set to `RANDOM` and doesn’t change during merges. Copying bytes from old segments to new ones is much faster than re-building the graph, so keeping `RANDOM` read advice makes the most sense. For flat formats, the read advice is set to `SEQUENTIAL`, as brute-force is the only way to retrieve nearest neighbors. This is a deliberate decision to keep things simple and predictable. While it might seem like a step back compared to #13985, using multiple read advices on the same file can lead to unpredictable behavior—it might seem fine until you test it in a constrained setup. That said, we could still improve merge performance with a `RANDOM` read advice in the future, for instance, by adding eager prefetching. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
