Re: Comparing RDBMS engines

> > Why is row-level locking so important? Page level locking is very > efficient. Furthermore, doesn't Online lock the entire page in a DML > transaction? Row level locking can be much more efficient than page level locking. This can be achieved by merely locking the first byte of a record in the underlying data file manager. DML stands for Data Manipulation Language if I understand correctly. All tables created in Informix that have row level locking switched on use row level locking in updates within DML statements. Perhaps you are referring to DDL. This would indeed lock the entire table being modified, which should always be the case. > > Every case of contention that I have encountered was better addressed > by spreading out the updates instead of increasing the granularity. > I am not too sure what you mean with spreading out updates. If this implies spreading updates in a serial batch fashion then I must disagree with you when it comes to interactive user driven systems. We, in fact, discourage batch updates. We have had many examples where an entire system locks up due to the lack of page level locking. As I stated previously, RDBMS engines that do not support record level locking are limited when it comes to interactive systems. Theo