Over the night my database was running. Doing both insert (constant) and select jobs (incidental). It seems that the combination is fatal. Doing each thing on independant databases I don't have problems at all, but doing them within the same database all kind of badness arrises. The next badness is the internal sql log of 4GB, MonetDB reports disk full. Which is actually the case. The actual database contents is only 49MB upon start (after inserting static data). I expect 200.000 extra rows of dynamic data, with a cyclic pattern, to be added over a week time, overwritting eachother. I wonder if it could be related to 'no-autocommit' behavior of select queries outside of transactions. I would assume it does not make sense at all, but that seems the most 'logical' reason... I could recover from disk full to free up space, wait a long time with a high load. SQL log was empty. Please advise, Stefan