[infinispan-dev] Design change in Infinispan Query

[Mircea Markus]

On Jan 31, 2014, at 7:30 AM, Radim Vansa <rvansa at redhat.com> wrote:

> On 01/30/2014 08:51 PM, Mircea Markus wrote:
>> On Jan 30, 2014, at 9:42 AM, Galder Zamarreño <galder at redhat.com> wrote:
>> 
>>> On Jan 21, 2014, at 11:52 PM, Mircea Markus <mmarkus at redhat.com> wrote:
>>> 
>>>> On Jan 15, 2014, at 1:42 PM, Emmanuel Bernard <emmanuel at hibernate.org> wrote:
>>>> 
>>>>> By the way, people looking for that feature are also asking for a unified Cache API accessing these several caches right? Otherwise I am not fully understanding why they ask for a unified query.
>>>>> Do you have written detailed use cases somewhere for me to better understand what is really requested?
>>>> IMO from a user perspective, being able to run queries spreading several caches makes the programming simplifies the programming model: each cache corresponding to a single entity type, with potentially different configuration.
>>> Not sure if it simplifies things TBH if the configuration is the same. IMO, it just adds clutter.
>> Not sure I follow: having a cache that contains both Cars and Persons sound more cluttering to me. I think it's cumbersome to write any kind of querying with an heterogenous  cache, e.g. Map/Reduce tasks that need to count all the green Cars would need to be aware of Persons and ignore them. Not only it is harder to write, but discourages code reuse and makes it hard to maintain (if you'll add Pets in the same cache in future you need to update the M/R code as well). And of course there are also different cache-based configuration options that are not immediately obvious (at design time) but will be in the future (there are more Persons than Cars, they live longer/expiry etc): mixing everything together in the same cache from the begging is a design decision that might bite you in the future.
>> 
>> The way I see it - and very curious to see your opinion on this - following an database analogy, the CacheManager corresponds to an Database and the Cache to a Table. Hence my thought that queries spreading multiple caches are both useful and needed (same as query spreading over multiple tables).
> I would be all hands for this approach, but there's still one thing 
> where it makes sense - Animal cache with Cats and Dogs.

Not a good idea to keep cats and dogs together :-)
Would it be a problem iff the user works with Animals only?

Cheers,
-- 
Mircea Markus
Infinispan lead (www.infinispan.org)