Cancel usage of chunk_number if loading the whole dependency (#894)

* Cancel usage of `chunk_number` if loading the whole dependency

* Add argument of whether check data_type is stored

* Add `strax_version`

strax/context.py

@@ -2384,22 +2384,27 @@ def merge_per_chunk_storage(
         rechunk=True,
         chunk_number_group: ty.Optional[ty.List[ty.List[int]]] = None,
         target_frontend_id: ty.Optional[int] = None,
+        check_is_stored: bool = True,
     ):
         """Merge the per-chunked data from the per-chunked dependency into the target storage."""
 
-        if self.is_stored(run_id, target):
+        if check_is_stored and self.is_stored(run_id, target):
             raise ValueError(f"Data {target} for {run_id} already exists.")
 
         self._check_merge_per_chunk_storage_kwargs(run_id, target, target_frontend_id)
 
+        chunks = self.get_metadata(run_id, per_chunked_dependency)["chunks"]
         if chunk_number_group is not None:
             combined_chunk_numbers = list(itertools.chain(*chunk_number_group))
             if len(combined_chunk_numbers) != len(set(combined_chunk_numbers)):
                 raise ValueError(f"Duplicate chunk numbers found in {chunk_number_group}")
-            _chunk_number = {per_chunked_dependency: combined_chunk_numbers}
+            if min(combined_chunk_numbers) == 0 and max(combined_chunk_numbers) == len(chunks) - 1:
+                # If the chunks are all the chunks of the dependency, we can drop the chunk_number
+                _chunk_number = None
+            else:
+                _chunk_number = {per_chunked_dependency: combined_chunk_numbers}
         else:
             # if no chunk numbers are given, use information from the dependency
-            chunks = self.get_metadata(run_id, per_chunked_dependency)["chunks"]
             chunk_number_group = [[c["chunk_i"]] for c in chunks]
             _chunk_number = None
 
@@ -2449,6 +2454,7 @@ def wrapped_loader():
         data_key = self.key_for(run_id, target, chunk_number=_chunk_number)
         target_plugin = self.__get_plugin(run_id, target, chunk_number=_chunk_number)
         target_md = target_plugin.metadata(run_id, target)
+        target_md["strax_version"] = strax.__version__
         # Copied from StorageBackend.saver
         if "dtype" in target_md:
             target_md["dtype"] = target_md["dtype"].descr.__repr__()