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. >
