Re: [incquery-dev] Model modification - local search vs RETE

[Ujhelyi Zoltán <ujhelyiz@xxxxxxxxxxxxxxxx>]

HI,

some minor clarification (before Gaben comes home correcting it :) ): if an element is removed from the containment hierarchy (without the use of EcoreUtil.delete), it is possible that there is still a cross-reference (non-containment) pointing to it. After that point the Base indexer/Rete does not consider this EObject indexed (thus will not part of any match set). On the other hand, local search may find this node via these cross-references (but it is not guaranteed, asit might rely on Base to reach that instance).

The main question/challange here is what to do with the inconsistency:
 1. Ignore it and tell all users not to provide such cases (problematic as we have a large base of existing code we want to be compatible with :) )
 2. Document it that here might be some issues, and live with the fact that the two engines are not equivalent
 3. Make sure that all results are still in the original containment hierarchy (depending on the model/indexer setup this may worsen performance)
 4. Something else I don’t see as clearly.

Sadly, none of my alternatives sound good to me, but I am/we are open to ideas…

Cheers,
Zoli
-- Zoltán Ujhelyi

Technology Expert
IncQueryLabs Ltd.

> On 08 Sep 2015, at 23:33, Márton Búr <marton.bur@xxxxxxxxx> wrote:
> 
> Dear All,
> 
> Today I ran into a problem, which is worth mentioning. I was running all the School tests to see the new local search algorithm (not yet merged into master) performing. Except for the recursive patterns, all other tests but two were passing. The two failures were caused by unexpected matches. 
> The problem briefly: local search based matcher is not considered* about the EMF notifications, however RETE matcher is. This difference may result in different matching results, especially in cases when the model is modified subsequently.
> I provided some details about this issue on page  https://wiki.eclipse.org/EMFIncQuery/DeveloperDocumentation/LocalSearch under KnownProblems.
> 
> Cheers,
> Marci
> 
> *this statement is basically true, when the matcher does not use the base index
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