> locks or deadlocks around the runtime. is it any easy way to avoid those > locks. This is a fairly complex subject. Here is a good place to start: http://db.apache.org/derby/docs/10.2/devguide/cdevconcepts30291.html Some of the tools under your control are: - use smaller transactions - ensure that tables have the right indexes - use the proper isolation level - update tables in a consistent order within transactions - use the FOR UPDATE clause when selecting rows in order to update them later in the same transaction - use the LOCK TABLE clause to force locking behavior It can take a while, but careful application design will enable you to have a high-performing, low-contention application. thanks, bryan