Dear MonetDB developers, using MonetDB-SQL Feb2010, I occasionally encounter this error message: bat_storage.mx:1274: tr_update_delta: Assertion `obat->ibase == cbat->ibase' failed It occurs only seldomly, so I'll probably not have an isolated test case all too soon. I wonder if someone with more insight into the SQL engine has some pointers on where to look at. Many thanks, Isidor Zeuner