On 4 mars 2013, at 17:39, Sanne Grinovero <sa...@hibernate.org> wrote:
> On 4 March 2013 16:20, Emmanuel Bernard <emman...@hibernate.org> wrote:
>> I already gave what I knew on how to load an entity from a tuple (which
>> isn't much) but we can try and dig together. Something I thought about
>> is that ORM probably has a mechanism to load an entity from a resultset
>> via the query parser. And that probably looks also like the second half
>> of OgmLoader.load. We could look at this part and see if we can make an
>> OGM version of it. We never had the need before as we never had query
>> support (the way SQL does it).
>
> I would also need to study the ORM code, but to add a high level observation,
> the methods currently defined by the GridDialect are focusing on
> loading from well known key instances,
> there is nothing to makes us able to scan/inspect for all values.
>
> In other words: even if we wanted to load keys first, we don't have
> definitions
> of functions from raw->primary key instances either.
I understand that. I'm not denying the need for the method.
>
>
>> On the visitor vs Iterator approach, I still don't see how implementing
>> an Iterator on a map / reduce backend would be harder than the visitor
>> but maybe I'm missing something.
>>
>> class IteratorAsStream {
>> final Query someMapReduceQuery = ...;
>>
>> public Object next() {
>> if (!someMapReduceQuery.started()) {
>> // execute and collect results in parallel
>> someMapReduceQuery.execute();
>> }
>> Object result = someMapReduce.getNextOrBlock();
>> return result;
>> }
>> }
>
> That could work to *load* all entities in parallel, but I'd like to
> process the entities in parallel as well.
> And I'd rather not force the GridDialect implementors to write some
> Hibernate Search specific code,
> so to break out we need some form of "Execute X on each": a closure or a
> lambda.
>
I can't see how the visitor model helps in your processing of entities in
parallel. To me both approaches are strictly equivalent. Care to show some
pseudo-code?
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