Hi I heve finally installed the PopyDA0.7 that is a Multithreaded DA (multiple concurrent access on the DBMS) Now I'm doing tests to verify the DBMS transactions (Postgress support DB transations): But something doesn't work as expected: I summarize my tests: I have two DTML Documents: first DTML: now called D1 <dtml-var header> ...1st sql statement: select * from customers where name='white' ...time.sleep(10) #external function that invokea the sleep function (10 sec) ...2dn sql statement: update customer set descr='Updated 1' where customer='white' <dtml-var footer> Second DTML: now called D2 <dtml-var header> ...sql statement: update customer set descr='Updated 2' where customer='white' <dtml-var footer> with two browser I called: D1 and then D2 My expected Behaviour was: -With the first statement of D1, Postgres would locks the table The update of D2 has to wait to write because the table is locked only when D1 has finished, D2 commit As result the updated field has to result "Update 2" and not 'Update 1" With the option Auto-commit mode ON the Behaviour was: -D2 autocommit without waiting the end of D1! (as espected with autocomm. off) As result the updated field has to result "Update 1" (because D1 ended after D1) With the option Auto-commit mode OFF the Behaviour was: -D2 autocommit without waiting the end of D1!!!!!!!!!! Why??????!?!??!? -When D1 finished an error occurs: Error Type: ProgrammingError Error Value: ERROR: Can't serialize access due to concurrent update As result the updated field has to result "Update 2" FAULT!! HOW CAN I HAVE TO DO in order to build a concurrent transaction Application with Popy and Postgress??? Thank you Very Much for your Help! Paolo Quaglia Information Technology Coordinator Sitek S.p.A. paolo@sitek.it