[jira] [Commented] (JENA-803) Custom aggregates in SPARQL.

["Rob Vesse (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14707157#comment-14707157 ] 

Rob Vesse commented on JENA-803:
--------------------------------

Circling back to this because I finally have some time to work on this again

The basic syntax and API looks fine and I don't forsee any difficulties in adopting it in our architecture.  One thing that I did however notice is that this syntax does not allow for the {{DISTINCT}} keyword e.g.

{noformat}
SELECT (AGG<http://custom>(DISTINCT ?s, ?o) AS ?result 
WHERE
{
  #...
}
{noformat}

Would this even make sense or should the assumption be that dealing with the distinctness (if desired) would simply be a property of a specific custom aggregate, so you might have {{<http://custom>}} and {{<http://customDistinct>}} as separately registered custom aggregates.

Any thoughts?  I'm leaning towards the separate URIs approach though I can also see a case being made for the {{DISTINCT}} keyword approach

> Custom aggregates in SPARQL.
> ----------------------------
>
>                 Key: JENA-803
>                 URL: https://issues.apache.org/jira/browse/JENA-803
>             Project: Apache Jena
>          Issue Type: New Feature
>          Components: ARQ
>    Affects Versions: Jena 2.12.1
>            Reporter: Andy Seaborne
>            Assignee: Andy Seaborne
>             Fix For: Jena 2.13.0
>
>
> Support SPARQL custom aggregates.



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