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From "Paolo Castagna (JIRA)" <>
Subject [jira] [Commented] (JENA-111) Improving TopN optimization in case of an intermediate OpModifier
Date Tue, 06 Sep 2011 20:03:10 GMT


Paolo Castagna commented on JENA-111:

> but, by using subSELECTs, you can write any sequence you want. 

This line confused me, rather than clarify.

My understand is that if we handle the project we have covered all the possibilities between
slice and order algebra operators, right?

Sara's proposal seems a good idea to me and I did not spotted initially. 

Are there other situations where an algebra operator between slice and order will inhibit
the optimizations in JENA-89 and JENA-109?

> Improving TopN optimization in case of an intermediate OpModifier
> -----------------------------------------------------------------
>                 Key: JENA-111
>                 URL:
>             Project: Jena
>          Issue Type: Improvement
>          Components: ARQ
>            Reporter: Sara Magliacane
>            Assignee: Paolo Castagna
>            Priority: Minor
>              Labels: arq, optimization
>         Attachments: topk_project.patch
> In the TopN optimization (Jena-89)  it would be useful to handle also the case in which
there are some other OpModifiers (I think they are the only category of Ops that can be in
that position in the tree) between Slice and Order By, for example OpProject:
> (slice _1
>   (project ?s ...
>     (order by <condition>
> -> 
> (project ?s ...
>   (top 1 <condition>

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