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From "Marcel Reutegger (JIRA)" <j...@apache.org>
Subject [jira] Updated: (JCR-1872) Improve performance of simple path queries
Date Fri, 21 Nov 2008 14:58:44 GMT

     [ https://issues.apache.org/jira/browse/JCR-1872?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Marcel Reutegger updated JCR-1872:
----------------------------------

    Attachment: image001.png

The diagram shows query timings (microsecond, logarithmic scale). From top to bottom:

- previous implementation (CPU bound, average 340 milliseconds)
- with recent changes, average time is now 20 milliseconds (the limiting factor now is disc
latency because of the random node lookup)
- with recent changes but in addition the derby database is now on a flash disk, average time
is now below 10 milliseconds

> Improve performance of simple path queries
> ------------------------------------------
>
>                 Key: JCR-1872
>                 URL: https://issues.apache.org/jira/browse/JCR-1872
>             Project: Jackrabbit
>          Issue Type: Improvement
>          Components: jackrabbit-core
>            Reporter: Marcel Reutegger
>            Priority: Minor
>             Fix For: 1.6.0
>
>         Attachments: image001.png
>
>
> Queries with simple path constraints can be quite slow because of the way they are implemented.
The current implementation basically does a hierarchical join with the context nodes and the
set of nodes with the name of the next location step. When the specified path is quite selective
the implementation should   rather resolve the path expression using the item state manager
(similar to how regular paths are resolved in the JCR API).

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