Add rechunking in fragments code and ROWID to columns in backup app.

quartical/apps/backup.py

@@ -67,7 +67,7 @@ def backup():
     # This call exists purely to get the relevant shape and dtype info.
     data_xds_list = xds_from_storage_ms(
         args.ms_path,
-        columns=column_name,
+        columns=(column_name, "ROWID"),
         index_cols=("TIME",),
         group_cols=("FIELD_ID", "DATA_DESC_ID", "SCAN_NUMBER"),
     )
@@ -81,7 +81,7 @@ def backup():
     # Repeat of above call but now with correct chunking information.
     data_xds_list = xds_from_storage_ms(
         args.ms_path,
-        columns=column_name,
+        columns=(column_name, "ROWID"),
         index_cols=("TIME",),
         group_cols=("FIELD_ID", "DATA_DESC_ID", "SCAN_NUMBER"),
         chunks=chunks

quartical/data_handling/ms_handler.py

@@ -8,6 +8,7 @@
     xds_from_table_fragment,
     xds_to_table_fragment
 )
+from daskms.experimental.utils import rechunk_by_size
 from dask.graph_manipulation import clone
 from loguru import logger
 from quartical.weights.weights import initialize_weights
@@ -300,6 +301,12 @@ def write_xds_list(xds_list, ref_xds_list, ms_path, output_opts):
         warnings.simplefilter("ignore")
 
         if output_opts.fragment_path:
+
+            xds_list = [
+                rechunk_by_size(xds, {'corr'}, only_when_needed=True)
+                for xds in xds_list
+            ]
+
             write_xds_list = xds_to_table_fragment(
                 xds_list,
                 output_opts.fragment_path,