Hi, PL/Java implements JDBC Savepoints using BeginInternalSubTransaction/ ReleaseCurrentSubTransaction/RollbackAndReleaseCurrentSubTransaction.
That seems to be the Accepted Way of Doing Things within backend PLs that want control over error recovery, am I right? PL/Java also strictly enforces that such a subxact set within a Java function must be released or rolled back by the time that function returns. The reasoning there is less obvious to me; my intuition would have been that a subtransaction could remain in play for the life of its containing transaction, which could have been started outside of this Java function; by holding a reference to the JDBC Savepoint object, a later Java function called in the same transaction could release it or roll it back. But I am beginning to suspect that the limitation may be essential, given the comments in xact.c around StartSubTransaction and how its effects would get clobbered on exit from a Portal, so a subxact started by an actual SAVEPOINT is started in two steps, the later one after the Portal has exited. By contrast, within a function (being executed inside a Portal?), I have to use BeginInternalSubTransaction, which combines the multiple steps into one, but whose effects wouldn't survive the exit of the Portal. Have I reverse-engineered this reasoning correctly? If so, I'll add some comments about it in the PL/Java code where somebody may be thankful for them later. Or, if it turns out the limitation isn't so inescapable, and could be relaxed to allow a subxact lifetime longer than the single function that starts it, I could look into doing that. Thanks! -Chap
