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From Dmitry Pavlov <dpavlov....@gmail.com>
Subject Re: Logical Cache Documented
Date Tue, 03 Oct 2017 19:54:10 GMT
+1 to Vladimir. I think it is better to keep this feature disabled by
default. And enable cache groups only in case this feature is required by
user needs.

Enabling this will cause all caches will be placed into one tree.

After collapsing all B+-trees into one we will get log(N1+N2+N3) instead of
log(N1) complexity.

вт, 3 окт. 2017 г. в 22:48, Denis Magda <dmagda@apache.org>:

> Vladimir,
>
> Please share more details that I can put on the paper. Presently the
> feature is described as a must have and I struggled finding any negative
> impact related info.
>
> —
> Denis
>
> > On Oct 3, 2017, at 12:46 PM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
> >
> > Denis,
> >
> > This feature should not be enabled by default as it negatively affects
> read
> > performance.
> >
> > On Tue, Oct 3, 2017 at 10:31 PM, Denis Magda <dmagda@apache.org> wrote:
> >
> >> Sam,
> >>
> >> Is there any technical limitation that prevents us from assigning caches
> >> with similar parameters to relevant groups on-the-fly?
> >>
> >> After finishing the doc, I’m convinced the feature should be enabled by
> >> default unless there are some pitfalls not known by me.
> >>
> >> BTW, decided to avoid logical caches term usage falling back to vivid
> >> cache groups notion:
> >> https://apacheignite.readme.io/docs/cache-groups <
> >> https://apacheignite.readme.io/docs/cache-groups>
> >>
> >> —
> >> Denis
> >>
> >>> On Oct 3, 2017, at 12:10 AM, Semyon Boikov <sboikov@gridgain.com>
> wrote:
> >>>
> >>> Hi,
> >>>
> >>> Regarding question about  default cache group: by default cache groups
> >> are
> >>> not enabled, each cache is started in separate group. Cache group is
> >>> enabled only if groupName is set in CacheConfiguration.
> >>>
> >>> Thanks
> >>>
> >>> On Sat, Sep 30, 2017 at 11:55 PM, <dsetrakyan@apache.org> wrote:
> >>>
> >>>> Why not? Obviously compression would have to be enabled per group, not
> >> per
> >>>> cache.
> >>>>
> >>>> ⁣D.​
> >>>>
> >>>> On Sep 29, 2017, 10:50 PM, at 10:50 PM, Vladimir Ozerov <
> >>>> vozerov@gridgain.com> wrote:
> >>>>> And it will continue hitting us in future. For example, when data
> >>>>> compression is implemented, for logical caches compression rate
will
> be
> >>>>> poor, as it would be impossbile to build efficient dictionaries
in
> >>>>> mixed
> >>>>> data pages.
> >>>>>
> >>>>> On Sat, Sep 30, 2017 at 8:48 AM, Vladimir Ozerov <
> vozerov@gridgain.com
> >>>
> >>>>> wrote:
> >>>>>
> >>>>>> Folks,
> >>>>>>
> >>>>>> Honesly, to me logical caches appears to be a dirty shortcut
to
> >>>>> mitigate
> >>>>>> some inefficient internal implementation. Why can't we merge
> >>>>> partition maps
> >>>>>> in runtime? This should not be a problem for context-independent
> >>>>> affinity
> >>>>>> functions (e.g. RendezvousAffinityFunction). From user perspective
> >>>>> logic
> >>>>>> caches feature is:
> >>>>>> 1) Bad API. One cannot define group configuration. All you can
do is
> >>>>> to
> >>>>>> define group name on cache lavel and hope that nobody started
> another
> >>>>> cache
> >>>>>> in the same group with different configuration before.
> >>>>>> 2) Performance impact for scans, as you have to iterate over
mixed
> >>>>> data.
> >>>>>>
> >>>>>> Couldn't we fix partition map problem without cache groups?
> >>>>>>
> >>>>>> On Sat, Sep 30, 2017 at 2:35 AM, Denis Magda <dmagda@apache.org>
> >>>>> wrote:
> >>>>>>
> >>>>>>> Guys,
> >>>>>>>
> >>>>>>> Another question. Does this capability enabled by default?
If yes,
> >>>>> how do
> >>>>>>> we decide which group a cache goes to?
> >>>>>>>
> >>>>>>> —
> >>>>>>> Denis
> >>>>>>>
> >>>>>>>> On Sep 29, 2017, at 3:58 PM, Denis Magda <dmagda@apache.org>
> >>>>> wrote:
> >>>>>>>>
> >>>>>>>> Igniters,
> >>>>>>>>
> >>>>>>>> I’ve put on paper the feature from the subj:
> >>>>>>>> https://apacheignite.readme.io/docs/logical-caches <
> >>>>>>> https://apacheignite.readme.io/docs/logical-caches>
> >>>>>>>>
> >>>>>>>> Sam, will appreciate if you read through it and confirm
I
> >>>>> explained the
> >>>>>>> topic 100% technically correct.
> >>>>>>>>
> >>>>>>>> However, are there any negative impacts of having logical
caches?
> >>>>> This
> >>>>>>> page has “Possible Impacts” section unfilled:
> >>>>>>>> https://cwiki.apache.org/confluence/display/IGNITE/Logical+Caches
> >>>>> <
> >>>>>>> https://cwiki.apache.org/confluence/display/IGNITE/Logical+Caches>
> >>>>>>>>
> >>>>>>>> —
> >>>>>>>> Denis
> >>>>>>>
> >>>>>>>
> >>>>>>
> >>>>
> >>
> >>
>
>

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