ignite-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Vladimir Ozerov <voze...@gridgain.com>
Subject Re: MVCC configuration
Date Tue, 19 Sep 2017 09:34:26 GMT
What I mean is that it might be not applicable for DML by design. E.g. may
be we will have to fallback to per-memory-policy approach, or to
per-cache-group. As we do not know it at the moment and there is no clear
demand from users, I would simply put it aside to avoid in mess in public
API in future.

Moreover, per-cache flag raises additional questions which can be put out
of scope otherwise. E.g. is it legal to mix MVCC and non-MVCC caches in a
single transaction? If yes, what is the contract? Without fine-grained
per-cache approach in the first iteration we can avoid answering it.

On Tue, Sep 19, 2017 at 12:25 PM, Semyon Boikov <sboikov@gridgain.com>
wrote:

> If it is not valid for DML then we can easily detect this situation and
> throw exception, but if I do not use DML why non make it configurable
> per-cache?
>
> On Tue, Sep 19, 2017 at 12:22 PM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>
> > I would say that per-cache configuration should be out of scope as well
> for
> > the first iteration. Because we do not know whether it will be valid for
> > DML.
> >
> > On Tue, Sep 19, 2017 at 12:15 PM, Semyon Boikov <sboikov@gridgain.com>
> > wrote:
> >
> > > Folks, thank you for feedback, I want to summarize some decisions:
> > >
> > > 1. Mvcc is disabled by default. We'll add two flags to enable mvcc:
> > > per-cache flag - CacheConfiguration.isMvccEnabled, default value for
> all
> > > caches - IgniteConfiguration.isMvccEnabled.
> > > 2. For initial implementation mvcc for ATOMIC cache is out of scope, it
> > can
> > > be enabled only for TRANSACTIONAL caches.
> > > 3. Mvcc coordinator can be any server node (oldest server node is
> > selected
> > > automatically). Also I believe we need possibility to have *dedicated*
> > mvcc
> > > coordinator nodes which will process only internal mvcc messages. Node
> > can
> > > be marked as dedicated coordinator via new flag
> > > IgniteConfiguration.isMvccCoordinator or we can add separate
> > > MvccConfiguration bean. But let's skip this decision for now before we
> > have
> > > benchmarks numbers.
> > > 4. Need add some metrics to monitor mvcc coordinator performance.
> > >
> > >
> > > Thanks
> > >
> > > On Tue, Sep 19, 2017 at 10:47 AM, Vladimir Ozerov <
> vozerov@gridgain.com>
> > > wrote:
> > >
> > > > This could be something like "preferredMvccCoordinator".
> > > >
> > > > On Tue, Sep 19, 2017 at 10:40 AM, Alexey Goncharuk <
> > > > alexey.goncharuk@gmail.com> wrote:
> > > >
> > > > > >
> > > > > > I agree that we need coordinator nodes, but I do not understand
> why
> > > > can't
> > > > > > we reuse some cache nodes for it? Why do we need to ask user
to
> > start
> > > > up
> > > > > > yet another type of node?
> > > > > >
> > > > >
> > > > > Dmitriy,
> > > > >
> > > > > My understanding is that Semyon does not deny a cache node to be
> used
> > > as
> > > > a
> > > > > coordinator. This property will allow to optionally have a
> > *dedicated*
> > > > node
> > > > > serving as a coordinator to improve cluster throughput under heavy
> > > load.
> > > > >
> > > >
> > >
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message