Add retrieve all item_id for each field assosiated to a notes

src/calibre/db/backend.py

@@ -975,6 +975,9 @@ class DB:
     def notes_data_for(self, field_name, item_id):
         return self.notes.get_note_data(self.conn, field_name, item_id)
 
+    def get_notes_id_map(self):
+        return self.notes.get_note_id_map(self.conn)
+
     def set_notes_for(self, field, item_id, doc: str, searchable_text: str, resource_hashes, remove_unused_resources) -> int:
         id_val = self.tables[field].id_map[item_id]
         note_id = self.notes.set_note(self.conn, field, item_id, id_val, doc, resource_hashes, searchable_text)

src/calibre/db/cache.py

@@ -686,6 +686,10 @@ class Cache:
         ' Return all notes data as a dict or None if note does not exist '
         return self.backend.notes_data_for(field, item_id)
 
+    def get_notes_id_map(self) -> dict:
+        ' Return all item_id for each field assosiated to a notes. '
+        return self.backend.get_notes_id_map()
+
     @read_api
     def field_supports_notes(self, field) -> bool:
         ' Return True iff the specified field supports notes '

src/calibre/db/notes/connect.py

@@ -269,6 +269,14 @@ class Notes:
                 'resource_hashes': frozenset(self.resources_used_by(conn, note_id)),
             }
 
+    def get_note_id_map(self, conn):
+        rslt = {}
+        for (note_id, field_name) in conn.execute('SELECT id,colname FROM notes_db.notes'):
+            if field_name not in rslt:
+                rslt[field_name] = []
+            rslt[field_name].append(note_id)
+        return rslt
+
     def rename_note(self, conn, field_name, old_item_id, new_item_id, new_item_value):
         note_id = self.note_id_for(conn, field_name, old_item_id)
         if note_id is None: