Re: same cache cannot update twice in one transaction

[Павлухин Иван <vo...@gmail.com>]

Hi,

MVCC in Ignite is targeted to provide transactional consistency
guarantees. I suppose that with eventually consistent 3rd party store
it would be impossible to give much guarantees in general. Do think
that such eventually consistent store will be widely used? What kind
of guarantees should it provide? Is it easy to use it properly?
Currently we do not have answers to these questions. Feedback is
appreciated.

Also I must say that MVCC feature is currently in beta stage and
limitations are listed in documentation [1].

[1] https://apacheignite.readme.io/docs/multiversion-concurrency-control#section-other-limitations

чт, 28 февр. 2019 г. в 22:34, xmw45688 <xw...@procurant.com>:
>
> Hi Ilya,
>
> It'd better if this was mentioned in Ignite Doc.
>
> It seems very limited if MVCC only supports  the Ignite native persistence.
> Yes, supporting MVCC in 3rd party persistence is challenging.  However, do
> we really need MVCC when the data from Cache (where MVCC already enabled) is
> ready to write to a 3rd party persistence store.   I think that an "eventual
> consistence" for writing cached data into a 3rd persistence layer seems
> sufficient when Ignite is used as cache stored, and the data in cache store
> is persistent.
>
> Does Ignite have a plan to support MVCC in cache layer and write the data
> from the cached store into a 3rd party persistence store with some limited
> feature like "eventual consistence".
>
> Can some gurus shed some lights on this subject?
>
>
>
>
>
> --
> Sent from: http://apache-ignite-users.70518.x6.nabble.com/



-- 
Best regards,
Ivan Pavlukhin

Re: same cache cannot update twice in one transaction

[xmw45688 <xw...@procurant.com>]

1. why do we need the storage (whether native or 3rd party)?  I need the
storage because 1) down time for production deployment. 2) the data in the
cache  may be crashed and All ignite clusters are completed down (sorry)

2. So I need a storage to store the  data that have been committed when
transactions are committed.  Do I have to care MVCC query in 3rd party
storage? No.  It's very difficult (if not possible) to achieve this goal
given people are using distributed NoSQL databases.   Can we directly query
Ignite native storage with MVCC without the caching layer running on top of
it?  

3. Comparing to the other database storage, Ignite native storage is
relative new.  The features to support ML, data mining are provided, but not
comprehensive like Apach Spark...  So questions are raised when the
integration of Ignite native storage or 3rd party storage with Spark - which
storage is better?

4. I think that Ignite should specialize in caching, MVCC on cache layer
(grid). Provide own native storage, ML, data mining feature are great, but
there is limited resource for this community to complete this mission. 
Leave the other specialized groups (exports) focusing on storage store, ML,
data mining, Block Chain...  

5.  Instead Ignite might focus on to integrate these things together to
build data-ecosystem.  I think that there are many dis-integrated, separated
data storage, cache, ML, Deep Learning, blockchain. To put these things
together, it needs visionary leaders, high skilled engineers.  Why can we
make our world life easier? 

6. Igniters, please focus the grid computing (cache), ACID-compliant
transaction, MVCC-enabled SQL in cache layer, and provide services to
integrate with the other storage, spark (ML), hyper ledge fabric or ethereum
or bitcoin (block chain).  



--
Sent from: http://apache-ignite-users.70518.x6.nabble.com/