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From "Davide Giannella (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (OAK-2023) Optimal index usage for XPath queries with "order by" combined with "or"
Date Wed, 02 Mar 2016 15:34:18 GMT

     [ https://issues.apache.org/jira/browse/OAK-2023?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Davide Giannella updated OAK-2023:
----------------------------------
    Fix Version/s: 1.4

> Optimal index usage for XPath queries with "order by" combined with "or"
> ------------------------------------------------------------------------
>
>                 Key: OAK-2023
>                 URL: https://issues.apache.org/jira/browse/OAK-2023
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: query
>            Reporter: Thomas Mueller
>            Assignee: Thomas Mueller
>              Labels: performance
>             Fix For: 1.4, 1.3.4
>
>
> XPath queries with "or" are converted to union, even if there is an "order by" clause.
In such cases, sorting is done in memory. See also OAK-2022.
> For some queries, it might be better to not use union, but use an ordered index instead.
This is tricky to decide up-front, but it would be possible to estimate the cost of both variants
and pick the one that seems better.



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