@@ 1,4 1,5 @@ 
 from json import dumps
+import os
 
 from sqlalchemy import (
     create_engine,

          
@@ 13,6 14,7 @@ from dbcache import (
 
 from tshistory import __version__
 from tshistory.tsio import timeseries as tshclass
+from tshistory import util
 
 
 VERSIONS = {}

          
@@ 164,13 166,53 @@ def migrate_series_versions(engine, name
     migrate_add_diffstart_diffend(engine, f'{namespace}.group', interactive)
 
 
+def populatedata(pid, cn, tsh, namespace, name, tablename):
+    diffsb = []
+    delete = []
+    for csid, idate, diff in util.diffs(cn, tsh, name, tablename, None, None):
+        if len(diff):
+            diffsb.append(
+                {
+                    'csid': csid,
+                    'diffstart': diff.index[0],
+                    'diffend': diff.index[-1]
+                }
+            )
+        else:
+            delete.append(
+                {
+                    'csid': csid,
+                    'idate': idate
+                }
+            )
+
+    if diffsb:
+        sql = (
+            f'update "{namespace}.revision"."{tablename}" '
+            f'set diffstart=%(diffstart)s, '
+            f'    diffend=%(diffend)s '
+            f'where id=%(csid)s'
+        )
+        cn.execute(
+            sql, diffsb
+        )
+
+    if delete:
+        print(f'{pid}: revs to delete:', ','.join(x['idate'].isoformat()
+                                                    for x in delete))
+        sql = (
+            f'delete from "{namespace}.revision"."{tablename}" '
+            f'where id = %(csid)s'
+        )
+        cn.execute(sql, [{'csid': x['csid']} for x in delete])
+
+
 def migrate_add_diffstart_diffend(engine, namespace, interactive, onlydata=False, cpus=1):
-    import os
     import signal
     import sys
     import multiprocessing
     from sqlalchemy import create_engine
-    from tshistory import util
+
     if onlydata:
         print(f'data migration for columns `diffstart` and `diffend` to {namespace}.revision')
     else:

          
@@ 223,56 265,12 @@ def migrate_add_diffstart_diffend(engine
             f'alter column tsend drop not null'
         )
 
-    def partition(alist, size):
-        for i in range(0, len(alist), size):
-            yield alist[i:i+size]
-
     def listchunks(alist, n):
         import numpy as np
         return list(
             np.array_split(np.array(alist), n)
         )
 
-    def populatedata(pid, cn, name, tablename):
-        diffsb = []
-        delete = []
-        for csid, idate, diff in util.diffs(cn, tsh, name, tablename, None, None):
-            if len(diff):
-                diffsb.append(
-                    {
-                        'csid': csid,
-                        'diffstart': diff.index[0],
-                        'diffend': diff.index[-1]
-                    }
-                )
-            else:
-                delete.append(
-                    {
-                        'csid': csid,
-                        'idate': idate
-                    }
-                )
-
-        if diffsb:
-            sql = (
-                f'update "{namespace}.revision"."{tablename}" '
-                f'set diffstart=%(diffstart)s, '
-                f'    diffend=%(diffend)s '
-                f'where id=%(csid)s'
-            )
-            cn.execute(
-                sql, diffsb
-            )
-
-        if delete:
-            print(f'{pid}: revs to delete:', ','.join(x['idate'].isoformat()
-                                                      for x in delete))
-            sql = (
-                f'delete from "{namespace}.revision"."{tablename}" '
-                f'where id = %(csid)s'
-            )
-            cn.execute(sql, [{'csid': x['csid']} for x in delete])
-
     # main
     tsh = tshclass(namespace)
     with engine.begin() as cn:

          
@@ 309,7 307,7 @@ def migrate_add_diffstart_diffend(engine
                 if not onlydata:
                     addattributes(cn, tablename)
                 if migdata or onlydata:
-                    populatedata(pid, cn, name, tablename)
+                    populatedata(pid, cn, tsh, namespace, name, tablename)
                 if not onlydata:
                     finalizeattributes(cn, tablename)
 

          
@@ 342,6 340,18 @@ def migrate_add_diffstart_diffend(engine
         )
 
 
+def migrate_seriesdata_diffstart_diffend(engine, namespace, name):
+    tsh = tshclass(namespace)
+    pid = os.getpid()
+
+    with engine.begin() as cn:
+        cn.cache = {'series_tablename': {}}
+        tablename = tsh._series_to_tablename(cn, name)
+        if tablename:
+            print(f'{pid}: migrating `{name}` (table: {tablename})')
+            populatedata(pid, cn, tsh, namespace, name, tablename)
+
+
 def migrate_metadata(engine, namespace, interactive):
     ns = namespace