OpenSearch VectorStore cannot return more than 4 retrieved result.

[gsdssn]

Using the following script, I can only return maximum 4 documents. With k = 1, k= 2, k=3, k = 4, k =5, k=6, ... similarity_search_with_score returns 1, 2, 3, 4, 4, 4... docs.

opensearch_url = "xxxxxxxxx.com"
docsearch = OpenSearchVectorSearch.from_documents(docs, 
                                                  embedding = HuggingFaceEmbeddings(), 
                                                  opensearch_url=opensearch_url, 
                                                  index_name="my_index_name")
retrieved_docs = docsearch.similarity_search_with_score(query, k=10)

This only return 4 documents even though I have len(docs) = 90+. Tried various indexes and various queries. Confirmed the issue is persistent.
Find a related issue (also max out at 4 regardless of k) for Chroma.

[gsdssn]

Using search_type="painless_scripting" would fix this issue. Sounds like this is only an issue for approximate search. Tried "faiss" and "nmslib", both have max retrieved documents = 4

[naveentatikonda]

@gsdssn you also need to set another parameter size for approximate search which is by default set to 4 like k.

k is the number of neighbors the search of each graph will return. You must also include the size option, which indicates how many results the query actually returns.

With this PR which Davis created you don't need to set the size parameter which will be same as k.