The post discusses an issue where the target document is returned after 100 items when the PDF includes 100 pages, but the community members can get the result in the top 20 when using a few pages. The comments suggest that the retrieval in llamaindex uses a similarity algorithm, so it should not have an issue even if the required content is present after 100 items. One community member suggests setting the similarity_top_k value to 20 to find the top 20 results based on the query. Another community member mentions the need to optimize the query or do query transformation to ensure the target answer appears in the top 20 results. The community members also discuss how to implement retrieval and query engine together, and how to fetch the retrieved nodes used for generating the response.