Why do i get different chunks returned when asking the same question over and over again?

Are you using a chat engine or agent? What vector store are you using?

possible neither 😄 just the original - index = GPTVectorStoreIndex.from_vector_store(vector_store=vector_store)

query_engine = index.as_query_engine(similarity_top_k=s_topk)

Using chromadb as the vector store

hmm, I know chroma has a very weird retrieval algorithm. Its approximate, so its definitely possible it changes slightly if you've indexed very similar chunks

Thank you - what is a good alternative which is more "precise"

anything using HNSW will be approximate. Other dbs have options for exact match methods like IVF etc.

Tbh though I see the most issues about wonky retrieval from chroma, but never any other vector db

So probably anything else