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https://issues.apache.org/jira/browse/OAK-622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13920868#comment-13920868
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Thomas Mueller commented on OAK-622:
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Revision 1574491 (WIP)
> Improve QueryIndex interface
> ----------------------------
>
> Key: OAK-622
> URL: https://issues.apache.org/jira/browse/OAK-622
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: query
> Reporter: Thomas Mueller
> Assignee: Thomas Mueller
> Priority: Minor
> Fix For: 1.0
>
> Attachments: OAK-622.patch
>
>
> The current QueryIndex interface is quite simple, but doesn't address some of
> the required features and more advanced optimizations that are possible:
> - For fulltext queries, it doesn't address the case where the index
> implementation has a different understanding of the fulltext condition than
> what is described in the JCR spec (the basic features).
> - For queries with "order by" it would be good to know if the index supports
> returning the data in sorted order, and if yes, how much slower that would be
> (if it is slower). So a index might have multiple strategies with different
> costs.
> - It's quite easy to misunderstand what getCost is supposed to do exactly.
> The new API should have a clearer solution here.
> - Even if the query doesn't have "order by", the index might return the data
> in a sorted way, which might help improving query performance (using a merge
> join)
> - The cost is currently a single value, it might be better to estimate the
> number of nodes, the cost to run a query, and the cost per node. That way we
> could optimize to quickly return the first few nodes (versus optimize for
> thoughput).
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