test fix for chromadb persistence bug

app_gradio.py

@@ -314,9 +314,14 @@ def run_rag_qa(query, papers_df, question_type):
         documents.append(doc)
 
     text_splitter = RecursiveCharacterTextSplitter(chunk_size=150, chunk_overlap=50, add_start_index=True)
+    
+    try:
+        del vectorstore, splits
+    except:
+        print('no vectorstore found, initializing')
     splits = text_splitter.split_documents(documents)
     vectorstore = Chroma.from_documents(documents=splits, embedding=embeddings, collection_name='retdoc4')
-    retriever = vectorstore.as_retriever(search_type="similarity", search_kwargs={"k": 6})
+    retriever = vectorstore.as_retriever(search_type="similarity", search_kwargs={"k": len(documents)})
 
     if question_type == 'Bibliometric':
         template = bibliometric_prompt