Hello Ivan, First of all, it looks like that EVT_CACHE_ENTRY_CREATED, > EVT_CACHE_ENTRY_DESTROYED are legacy came from Ignite 1.x time and have a > little value nowadays. Does anyone have something against deprecating them?
These events are used in a pure caching or in-memory data grid use cases where key-value is a primary access pattern. I personally know several companies who rely on those events. So, we can't discontinue them, not everyone uses SQL. What's a hurdle of making them working with MVCC? -- Denis On Fri, Sep 21, 2018 at 6:44 AM Павлухин Иван <vololo...@gmail.com> wrote: > Hi Igniters, > > As you might know MVCC was introduced in Apache Ignite. We started > IgniteEvents support implementation for MVCC caches and faced some > obstacles. I would like to start a discussion about next steps which should > be done to deal with current problems. The main theme is about > EventType.EVTS_CACHE and key-value API. > > First of all, it looks like that EVT_CACHE_ENTRY_CREATED, > EVT_CACHE_ENTRY_DESTROYED are legacy came from Ignite 1.x time and have a > little value nowadays. Does anyone have something against deprecating them? > > Second, there could be problems with EVT_CACHE_OBJECT_UNLOCKED event, > because for MVCC all locks are released on transaction end. And it does not > sound good idea to track all locked entries during transaction execution, > in MVCC we are not keeping entries modified participating in transaction in > private working set in memory. One possible solution is deprecation of > lock, unlock events. Another one is introducing special lock event for > MVCC, but it will be confusing. Also, I see an option of firing only > EVT_CACHE_OBJECT_LOCKED. > > Last, is different number of events fired for similar scenarios and > different cache modes. Let's consider "put, remove, put" for the same key > and different modes. For ATOMIC 2 put and 1 remove event will be fired. For > TRANSACTIONAL 1 put will be fired in case of commit and nothing in case of > rollback. For MVCC in current vision 2 put will be fired regardless whether > transaction was committed and rolled back. Currently I do not see options > how to overcome it. > > Also, I hardly imagine current use cases for cache events. I think that > understanding them is the best way for developing working solution for > MVCC. > > I need your opinions. > > 2018-09-21 12:54 GMT+03:00 Павлухин Иван <vololo...@gmail.com>: > > > Hi Igniters, > > > > As you might know MVCC was introduced in Apache Ignite. We started > > IgniteEvents implementation for MVCC caches and faced some obstacles. I > > would like to start a discussion about next steps which should be done to > > deal with current problems. > > > > -- > > Best regards, > > Ivan Pavlukhin > > > > > > -- > Best regards, > Ivan Pavlukhin >
