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From Denis Magda <dma...@apache.org>
Subject Re: Logical Cache Documented
Date Tue, 03 Oct 2017 19:48:34 GMT
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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