[Feature Request]: Opensearch efficient filtering about llama_index HOT 1 OPEN

I had a look in Haystack's implementation of their OpenSearchDocumentStore and they implement it as follows. But if I see this correctly, it should do simple post-search filtering which is not ideal. Although they state that

Filters are applied during the approximate kNN search to ensure that top_k matching documents are returned.

But according to the Opensearch blog post I linked above, the filters should be inside the knn-query, no?

body = {
    "query": {
        "bool": {
            "must": [
                {
                    "knn": {
                        "embedding": {
                            "vector": query_embedding,
                            "k": top_k,
                        }
                    }
                }
            ],
        }
    },
}

if filters:
    body["query"]["bool"]["filter"] = normalize_filters(filters)

body["size"] = top_k

from llama_index.