[infinispan-dev] multi-mapping with indexing - do we need big-table

[kapil nayar]

Hi Manik,

Actually, I started the thread on the user-forum. However, Sanne suggested
to discuss the use case on the developer's mailing list (see the link for
the user-forum discussion at the end of my last email).
"If you have suggestions or interesting use cases they are very welcome on
the developer's mailing list, or you can open feature requests directly on
JIRA if you have a very clear idea of your need already."

Albeit, I find this case interesting - let me know if this is trivial and we
can discuss it further on the user-forum.

Thanks,
Kapil

On Fri, Sep 9, 2011 at 5:56 AM, Manik Surtani <manik at jboss.org> wrote:

> Hi Kapil - please don't post such questions to this mail list; use the user
> forums instead.
>
> On 9 Sep 2011, at 05:23, kapil nayar wrote:
>
> We have two data sets {A1, A2, A3...} and {B1, B2, B3...}
> Each B has some associated data {C1, C2, C3....}  which has 1:1 mapping.
>
> The mappings would be something like (assume that C would be stored along
> side B):
> A1-> B1, B2
> A2-> B3, B5
> A3-> B4, B6, B7
>
> Now, we would need the following indexes:
> A->B and B->A
>
> Notice, that both are unique mappings. However, as shown A has multiple
> mappings to B.
> The big-table type of data structure allow this and make it pretty easy off
> the shelf.
>
> Now, I am trying to explore if we can implement these mappings with
> Infinispan.
> We may need a basic multi-map - to store multiple values for the same key
> in the cache.
>
> 1. The "get" would return the complete list of the values.
> 2. The "put" would add the new value without replacing the existing value.
> 3. The "remove" would remove a specific value or optionally all values
> associated with the key.
> 4. These operations (especially "put") on the same key can occur
> simultaneously from multiple nodes.
>
> I know there is an atomic map option in Infinispan which may be applicable,
> but AFAIK it requires transactions (which we want to avoid..).
>
> Alternatively, perhaps Infinispan (in combination with lucene) can be used.
> 1. We should be able to create data structure {B, C} and store A-> {B,C}
> with indexes defined for B.
> 2. Also, the key A could be structured as a combination of A+B to store
> multiple entries like A1B1->{B1,C1} and A1B2->{B2,C2}. Lucene would allow
> wild carded searches. e.g. To look for all A1 values we could do something
> like A1* which should return both A1B1 and A2B2....I may be making some
> assumptions here (feel free to correct!)
> 3. There seems to be one bottleneck though - since the cache mode is
> "distribution", it seems it is mandatory to use a backend DB to store these
> indexes and moreover the DB needs to be shared. This requirement actually
> seems to defeat the purpose of using Infinispan.
>
> Any ideas for achieving this implementation would be greatly appreciated.
>
> For reference this email is further to the user forum thread
> http://community.jboss.org/message/622996#622996
>
> Thanks,
> Kapil
>
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>
> --
> Manik Surtani
> manik at jboss.org
> twitter.com/maniksurtani
>
> Lead, Infinispan
> http://www.infinispan.org
>
>
>
>
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