[infinispan-dev] Design change in Infinispan Query

[Sanne Grinovero]

On 7 March 2014 15:55, Emmanuel Bernard <emmanuel at hibernate.org> wrote:
>
> On 07 Mar 2014, at 16:21, Sanne Grinovero <sanne at infinispan.org> wrote:
>
>
> Is it possible to use an index for x-cache joins with linear index update
> time and query?
>
>
> Index update cost is not linear but LogN: approximates to a constant
> cost. And we could cut this constant by 4 orders of magnitude if only
> I could safely differentiate between a put of a new entry vs. an
> update -> something which we'll need to brainstorm about.
>
> Query time is also significantly sub-linear in practice, but specifics
> will vary on the query type.
>
> Yes you could use indexes to improve x-cache joins, but you'll need an
> additional engine to coordinate that correctly, not least to manage
> data size buffers; essentially I think you'd need Teiid.
>
>
> I think Mircea means implementing joins across different caches if the
> foreign key is indexed.
>
> It would basically require N index seek (N being the number of fk value on
> your left hand side) per join and some aggregation engine to link the
> elements matching from the two side.
> So N^M
>
> M= # of joins
> N= # of distinct FK involved
>
> Does that reasoning sound right?

Right. Teiid.