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From Valentin Kulichenko <valentin.kuliche...@gmail.com>
Subject Re: Partition loss policy to disable cache completely
Date Wed, 24 Jan 2018 00:26:54 GMT
Yakov,

I still think there are valid use cases. From the top of my head - what if
one wants to iterate through multiple partitions and do some calculations?
Locking and transactional semantics are not needed, but if some of the data
is LOST, computation should fail, and new computations should not even
start. Basically, you assume that if two entries are stored in different
partitions and not accessed in same transaction, then these entries are
completely unrelated to each other. From my expirience, this assumption is
incorrect.

-Val

On Tue, Jan 23, 2018 at 11:03 AM, Yakov Zhdanov <yzhdanov@apache.org> wrote:

> Alex, I am against reducing cluster operation. I tried to explain in the
> prev email that it is impossible to have consistent approach here. You can
> prohibit operations only after exchange completes. However, in this case
> plenty of transactions are committed on previous cache topology having
> nodes they do not touch crashed/left the grid.
>
> --Yakov
>
> 2018-01-23 9:28 GMT-08:00 Alexey Goncharuk <alexey.goncharuk@gmail.com>:
>
> > Valentin,
> >
> > I am ok with having a policy which prohibits all cache operations, and
> this
> > is not very hard to implement. Although, I agree with Yakov - I do not
> see
> > any point in reducing cluster availability when operations can be safely
> > completed.
> >
> > 2018-01-23 2:22 GMT+03:00 Yakov Zhdanov <yzhdanov@apache.org>:
> >
> > > Val,
> > >
> > > Your suggestion to prohibit any cache operation on partition loss does
> > not
> > > make sense to me. Why should I care about some partition during
> > particular
> > > operation if I don't access it? Imagine I use data on nodes A and B
> > > performing reads and writes and node C crashes in the middle of tx.
> > Should
> > > my tx be rolled back? I think no.
> > >
> > > As far as difference it seems that IGNORE resets lost status for
> affected
> > > partitions and READ_WRITE_ALL does not.
> > >
> > > * @see Ignite#resetLostPartitions(Collection)
> > > * @see IgniteCache#lostPartitions()
> > >
> > > --Yakov
> > >
> > > 2018-01-17 14:36 GMT-08:00 Valentin Kulichenko <
> > > valentin.kulichenko@gmail.com>:
> > >
> > > > Folks,
> > > >
> > > > Our PartitionLossPolicy allows to disable operations on lost
> > partitions,
> > > > however all available policies allow any operations on partitions
> that
> > > were
> > > > not lost. It seems to me it can be very useful to also have a policy
> > that
> > > > completely blocks the cache in case of data loss. Is it possible to
> add
> > > > one?
> > > >
> > > > And as a side question: what is the difference between READ_WRITE_ALL
> > and
> > > > IGNORE policies? Looks like both allow both read and write on all
> > > > partitions.
> > > >
> > > > -Val
> > > >
> > >
> >
>

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