Sometimes can't delete an Oracle database row using Django

Question

I have a unit test which contains the following line of code

Site.objects.get(name="UnitTest").delete()

and this has worked just fine until now. However, that statement is currently hanging. It'll sit there forever trying to execute the delete. If I just say

print Site.objects.get(name="UnitTest")

then it works, so I know that it can retrieve the site. No other program is connected to Oracle, so it's not like there are two developers stepping on each other somehow. I assume that some sort of table lock hasn't been released.

So short of shutting down the Oracle database and bringing it back up, how do I release that lock or whatever is blocking me? I'd like to not resort to a database shutdown because in the future that may be disruptive to some of the other developers.

EDIT: Justin suggested that I look at the DBA_BLOCKERS and DBA_WAITERS tables. Unfortunately, I don't understand these tables at all, and I'm not sure what I'm looking for. So here's the information that seemed relevant to me:

The DBA_WAITERS table has 182 entries with lock type "DML". The DBA_BLOCKERS table has 14 entries whose session ids all correspond to the username used by our application code.

Since this needs to get resolved, I'm going to just restart the web server, but I'd still appreciate any suggestions about what to do if this problem repeats itself. I'm a real novice when it comes to Oracle administration and have mostly just used MySQL in the past, so I'm definitely out of my element.

EDIT #2: It turns out that despite what I thought, another programmer was indeed accessing the database at the same time as me. So what's the best way to detect this in the future? Perhaps I should have shut down my program and then queried the DBA_WAITERS and DBA_BLOCKERS tables to make sure they were empty.

Answer 1

From a separate session, can you query the DBA_BLOCKERS and DBA_WAITERS data dictionary tables and post the results? That will tell you if your session is getting blocked by a lock held by some other session, as well as what other session is holding the lock.