Not sure about readFromBackup, but changing PRIMARY_SYNC to FULL_SYNC looks safe to me. Any other thoughts?
ср, 2 авг. 2017 г. в 21:10, Denis Magda <dma...@apache.org>: > +1 for both suggestions but I’m not sure we can do the change till 3.0. > > — > Denis > > > On Aug 2, 2017, at 1:27 AM, Vladimir Ozerov <voze...@gridgain.com> > wrote: > > > > +1 for readFromBackup=false as well :-) Another example of default value > > with subtle effects. > > > > On Wed, Aug 2, 2017 at 11:11 AM, Alexey Goncharuk < > > alexey.goncha...@gmail.com> wrote: > > > >> Vladimir, > >> > >> Personally, I agree that we should put correctness over performance, > >> however (1) is not a correct statement for TRANSACTIONAL caches. A > >> transactional client always validates the result of an operation and > throw > >> a correct exception if operation failed. (1) is true for ATOMIC caches, > >> though. > >> > >> A user can get in trouble in this default for both TX and ATOMIC caches > if > >> a put is performed from a backup node and readFromBackup is set to > false. > >> In this case, the simple read-after-write scenario may fail. I would > rather > >> set readFromBackup to false by default, however, this fixes neither the > SQL > >> nor ATOMIC caches issues. > >> > >> +1 for the change, and extend the warning for partitioned caches with > >> readFromBackup=true and PRIMARY_SYNC. > >> > >> > >> > >> 2017-08-02 10:58 GMT+03:00 Vladimir Ozerov <voze...@gridgain.com>: > >> > >>> Igniters, > >>> > >>> I want to re-iterate idea of changing default synchronization mode from > >>> PRIMARY_SYNC to FULL_SYNC. > >>> > >>> Motivation: > >>> 1) If user set [cacheMode=PARTITIONED, backups=1] he still could loose > >> data > >>> silently. Because primary node could report success to the client and > >> then > >>> crash before data is propagated to backups. > >>> 2) If user set [cacheMode=REPLICATED] and use SQL, he will might get > >>> invalid results if cache is being updated concurrently - well known > >> issue. > >>> > >>> The only advantage of PRIMARY_SYNC is slightly better performance, but > we > >>> should prefer correctness over performance. > >>> > >>> Proposed changes: > >>> 1) Make FULL_SYNC default; > >>> 2) Print a warning about possibly incorrect SQL results if REPLICATED > >> cache > >>> is started in PRIMARY_SYNC mode. > >>> > >>> Thoughts? > >>> > >>> Vladimir. > >>> > >> > >
