There can be many reasons why a database is hanging. Except for the obvious locking problem, a full archive disk is also a possibility. An insert of a 300K long raw column will generate a lot of redo information. You mentioned that the application worked fine earlier, so maybe the disk had more free space then.

Anyway, I have sent you a document by e-mail, describing database hang-up diagnostics. Maybe this will provide a clue.

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Marco Kalter
Allround Automations