[jira] [Commented] (OAK-937) Query engine index selection tweaks: shortcut and hint

["Thomas Mueller (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15653545#comment-15653545 ] 

Thomas Mueller commented on OAK-937:
------------------------------------

Now that we have OAK-4888, I suggest we wait and see how that works, and depending on that either we close it as won't fix, or fix it later. 

> 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: core, query
>            Reporter: Alex Parvulescu
>            Assignee: Thomas Mueller
>            Priority: Minor
>              Labels: performance
>             Fix For: 1.6
>
>
> 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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