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https://issues.apache.org/jira/browse/OAK-937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16107080#comment-16107080
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Tommaso Teofili commented on OAK-937:
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I think this is a somewhat sensitive feature, my concern is that it can be
easily misused, as it exposes implementation details in a sort of API (the
query language syntax).
On the other hand I have seen cases where users would have liked to have such
syntax.
At the moment IMHO we are in a sort of middle ground where users can / have to
know how to define and use indexes but we also suggest not to touch certain
configurations or reindex in most of the cases.
Probably we should decide whether users should be caring about indexes or not,
or at least mark some features as experimental or expert so that users are less
unaware that they could shoot themselves in their feet.
> Query engine index selection tweaks: shortcut and hint
> ------------------------------------------------------
>
> Key: OAK-937
> URL: https://issues.apache.org/jira/browse/OAK-937
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: query
> Reporter: Alex Deparvu
> Assignee: Thomas Mueller
> Priority: Critical
> Labels: performance
> Fix For: 1.8
>
>
> This issue covers 2 different changes related to the way the QueryEngine
> selects a query index:
> Firstly there could be a way to end the index selection process early via a
> known constant value: if an index returns a known value token (like -1000)
> then the query engine would effectively stop iterating through the existing
> index impls and use that index directly.
> Secondly it would be nice to be able to specify a desired index (if one is
> known to perform better) thus skipping the existing selection mechanism (cost
> calculation and comparison). This could be done via certain query hints [0].
> [0] http://en.wikipedia.org/wiki/Hint_(SQL)
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