Fix: dynamically increase query params for higher k values (#131)

* fix: return enough results if k > ncells*32

* fix: increase both ndocs and ncells to match k

* chore: prepare release

* linting

* chore: saner ncells for larger datasets

* linting

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "RAGatouille"
-version = "0.0.6c1"
+version = "0.0.6c2"
 description = "Library to facilitate the use of state-of-the-art retrieval models in common RAG contexts."
 authors = ["Benjamin Clavie <ben@clavie.eu>"]
 license = "Apache-2.0"

ragatouille/__init__.py

@@ -1,4 +1,4 @@
-__version__ = "0.0.6c1"
+__version__ = "0.0.6c2"
 from .RAGPretrainedModel import RAGPretrainedModel
 from .RAGTrainer import RAGTrainer
 

ragatouille/models/colbert.py

@@ -422,14 +422,14 @@ def _load_searcher(
         )
 
         if not force_fast:
+            self.searcher.configure(ndocs=1024)
+            self.searcher.configure(ncells=16)
             if len(self.searcher.collection) < 10000:
-                self.searcher.configure(ncells=4)
+                self.searcher.configure(ncells=8)
                 self.searcher.configure(centroid_score_threshold=0.4)
-                self.searcher.configure(ndocs=512)
             elif len(self.searcher.collection) < 100000:
-                self.searcher.configure(ncells=2)
+                self.searcher.configure(ncells=4)
                 self.searcher.configure(centroid_score_threshold=0.45)
-                self.searcher.configure(ndocs=1024)
             # Otherwise, use defaults for k
         else:
             # Use fast settingss
@@ -459,6 +459,22 @@ def search(
             for doc_id in doc_ids:
                 pids.extend(self.docid_pid_map[doc_id])
 
+        base_ncells = self.searcher.config.ncells
+        base_ndocs = self.searcher.config.ndocs
+
+        if k > len(self.searcher.collection):
+            print(
+                "WARNING: k value is larger than the number of documents in the index!",
+                f"Lowering k to {len(self.searcher.collection)}...",
+            )
+            k = len(self.searcher.collection)
+
+        # For smaller collections, we need a higher ncells value to ensure we return enough results
+        if k > (32 * self.searcher.config.ncells):
+            self.searcher.configure(ncells=min((k // 32 + 2), base_ncells))
+
+        self.searcher.configure(ndocs=max(k * 4, base_ndocs))
+
         if isinstance(query, str):
             results = [self._search(query, k, pids)]
         else:
@@ -487,6 +503,10 @@ def search(
 
             to_return.append(result_for_query)
 
+        # Restore original ncells&ndocs if it had to be changed for large k values
+        self.searcher.configure(ncells=base_ncells)
+        self.searcher.configure(ndocs=base_ndocs)
+
         if len(to_return) == 1:
             return to_return[0]
         return to_return