1. delta did not scaled up on serialization; 2. beir script wrong pro…

…gress bar

scripts/benchmark_beir.py

@@ -65,20 +65,17 @@ def __init__(self, store: BetterBM25DocumentStore) -> None:
         self._store = store
         self._indexed = False
 
-    def index(self, corpus: dict[str, dict[str, str]]) -> int:
+    def index(self, corpus: dict[str, dict[str, str]]) -> None:
         """Index the corpus for retrieval."""
 
-        documents = []
         for idx, raw in tqdm.tqdm(corpus.items(), desc="Indexing corpus"):
             raw_title = raw.get("title", "")
             raw_text = raw.get("text", "")
 
             content = f"title: {raw_title}; text: {raw_text}"
             document = Document(idx, content=content)
-            documents.append(document)
-
+            self._store.write_documents([document])
         self._indexed = True
-        return self._store.write_documents(documents)
 
     def search(
         self,

src/bbm25_haystack/bbm25_store.py

@@ -315,7 +315,7 @@ def to_dict(self) -> dict[str, Any]:
             self,
             k=self.k,
             b=self.b,
-            delta=self.delta,
+            delta=self.delta * (self.k + 1.0),  # Because we scaled it on init
             sp_file=self._sp_file,
             haystack_filter_logic=self._haystack_filter_logic,
         )