Re: Detecting uncommitted changes

Thomas Kellerer <spam_eater@gmx.net> writes:
> Bill Moran wrote on 27.12.2011 19:37:
>>> is there a way I can detect if the current session has any uncommitted changes?

>> If I'm understanding you correctly, you could just make it check the
>> transaction status.  If there's an active transaction, then there are
>> "uncommitted changes".

> Sounds like what I want, but how do I check the "transaction status" (I'm using JDBC)

More specifically, look to see if the current transaction has assigned
itself a transaction ID.  I think the easiest place to see this is in
pg_locks --- it will be holding exclusive lock on a TransactionId object
if so.

There are various cases where you could get a false positive from this
type of test, eg if a subtransaction made some changes and then rolled
back, you'll have an XID even though there's not really anything to
commit.  But it will never give a false negative.

            regards, tom lane