> On Jan. 21, 2016, 12:28 p.m., John Sirois wrote: > > IIUC the MVCC capabilities in 1.4+ should prevent table locks on all but > > DDL stuff. > > John Sirois wrote: > Hmm - more to the story: "If MVCC is enabled, changing the lock mode > (LOCK_MODE) has no effect." ... Maybe turning on MVCC is worth some perf > tests or have you already been down that road? > > Maxim Khutornenko wrote: > I suggest a cautios approach to enabling MVCC as our previous experience > showed unacceptable performance with any meaningful amounts of data.
Bigger caution for me is that MVCC is considered beta in H2. > On Jan. 21, 2016, 12:28 p.m., John Sirois wrote: > > src/main/java/org/apache/aurora/scheduler/storage/db/DbModule.java, line 115 > > <https://reviews.apache.org/r/42613/diff/1/?file=1204582#file1204582line115> > > > > Please fix the comment and add a pointer to > > http://www.h2database.com/html/advanced.html?highlight=LOCK_MODE&search=LOCK#transaction_isolation > > since "3" is so cryptic and folks - like me just now - will want to double > > check. Agreed, fixed. - Bill ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/42613/#review115684 ----------------------------------------------------------- On Jan. 21, 2016, 12:25 p.m., Bill Farner wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/42613/ > ----------------------------------------------------------- > > (Updated Jan. 21, 2016, 12:25 p.m.) > > > Review request for Aurora, John Sirois and Zameer Manji. > > > Bugs: AURORA-1580 > https://issues.apache.org/jira/browse/AURORA-1580 > > > Repository: aurora > > > Description > ------- > > Proposing this as the minimal fix for AURORA-1580. I think it's wise, > however, to look towards the alternative approach i described in that ticket > for simplicity and performance gains. > > I'd like to note that after this change, it will be important to treat > long-running transactions carefully. It will be important to avoid > transactions block others by writing (locking a table) and subsequently doing > other lengthy work. > > > Diffs > ----- > > src/main/java/org/apache/aurora/scheduler/storage/db/DbModule.java > 2b3ee7bf6f7801c140f921b25f78daf6d320098a > src/main/resources/org/apache/aurora/scheduler/storage/db/TaskMapper.xml > e689cfeda39e1f065ed29c61a23376512df8f3aa > > src/test/java/org/apache/aurora/scheduler/storage/AbstractTaskStoreTest.java > 3dba286556ab6ea34b7fdd38508a164c902d9d17 > > Diff: https://reviews.apache.org/r/42613/diff/ > > > Testing > ------- > > > Thanks, > > Bill Farner > >
