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From Valentin Kulichenko <valentin.kuliche...@gmail.com>
Subject Re: Versioned entry scope usage
Date Thu, 30 Jul 2015 19:16:29 GMT
On Thu, Jul 30, 2015 at 6:36 AM, Dmitriy Setrakyan <dsetrakyan@apache.org>
wrote:

> On Thu, Jul 30, 2015 at 6:30 AM, Denis Magda <dmagda@gridgain.com> wrote:
>
> > Igniters,
> >
> > I've been working on the task that will let the user to retrieve version
> > related information for a particular Cache.Entry object.
> > All the details are here:
> https://issues.apache.org/jira/browse/IGNITE-946
> >
> > VersionedEntry of a given Cache.Entry can be retrieved by a call to
> > 'Cache.Entry.unwrap(VersionedEntry.class)'.
> > I've already fully supported 'unwrap' for Cache.Entry when it is returned
> > from:
> > - Cache.invoke();
> > - Cache.invokeAll();
> > - IgniteCache.randomEntry();
> >
> > The following entry points are left:
> > - Cache.iterator();
> > - IgniteCache.localEntries().
> >
> > However, I doubt that it makes sense to support these two last methods.
> > In my understanding a use case scenario of VersionedEntry is the
> > following: the user get a VersionedEntry for a particular key(s) using
> > Cache.invoke, keeps it and then compares with other VersionEntries for
> the
> > same key retrieved later.
> > I don't think that the user will iterate over a cache using
> > Cache.iterator() or IgniteCache.localEntries() in order to get a version,
> > especially in production.
> >
>
> Denis, what is the reason for not supporting a version on an entry at all
> times? Is there a specific performance issue or slow down you are concerned
> with?
>
>
>From my understanding, version is available only on the node where the
entry is stored and we never send it to client (for performance reasons
obviously). For example, in continuous query you can acquire version in the
remote filter, but not in local listener.


>
> >
> > What do you think? Do you see any other real life scenarios I'm missing?
> >
> > --
> > Denis
> >
>

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