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https://issues.apache.org/jira/browse/JENA-109?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paolo Castagna updated JENA-109:
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Attachment: JENA-109_ARQ_r1164652.patch
A little bit more testing is necessary, however this shows my proposal.
What do you think?
> Optimise ORDER BY + OFFSET + LIMIT queries
> ------------------------------------------
>
> Key: JENA-109
> URL: https://issues.apache.org/jira/browse/JENA-109
> Project: Jena
> Issue Type: Improvement
> Components: ARQ
> Reporter: Paolo Castagna
> Priority: Minor
> Labels: optimization, sparql
> Attachments: JENA-109_ARQ_r1164652.patch
>
>
> The benefits of JENA-89 gets lost as soon as someone uses OFFSET, even for
> low values.
> Maybe we can assume users will not hit 'next page' too many times.
> We can increase the TOPN_LIMIT_THRESHOLD in TransformTopN to 100000 (?) and
> apply the same TopN optimization we discussed in JENA-89 even when we have
> OFFSET (when OFFSET + LIMIT < TOPN_LIMIT_THRESHOLD).
> In QueryIterTopN we simply return IteratorArray.create(y, offset,
> offset+limit) instead of IteratorArray.create(y).
> This way we can avoid total sort for a few number of small pages (all within
> the 100000 threshold).
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