[jira] [Commented] (JENA-1988) Separating B+ tree into different Node representations.

["Andy Seaborne (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17227482#comment-17227482 ] 

Andy Seaborne commented on JENA-1988:
-------------------------------------

Could you explain what optimization hopes to achieve?

The native NodeTable has a large cache in front of it which benefits read-access, and many literals are encoded into NodeIds and don't hit the storage NodeTableNative.


> Separating B+ tree into different Node representations.
> -------------------------------------------------------
>
>                 Key: JENA-1988
>                 URL: https://issues.apache.org/jira/browse/JENA-1988
>             Project: Apache Jena
>          Issue Type: Question
>          Components: TDB
>    Affects Versions: Jena 3.16.0
>            Reporter: Martin Pekár
>            Priority: Blocker
>              Labels: features, newbie, performance, test
>             Fix For: Jena 3.16.0
>
>         Attachments: NodeTableNative.java
>
>
> In a project to optimize the indexing, I am trying to have 4 indexes, one for each Node type (variable, literal, URI and blank). To implement this, I added 4 copies of the _nodeHashToId_ Index instance in the _NodeTableNative_ class. Then, for every operation on the _nodeHashToId_, for example using _containsNode()_ in the NodeTableNative class, I first check the type of Node given as parameter and then check for existence in the appropriate _nodeHashToId_ copy.
> Now, for some reason I get a NullPointerException when running the tests. Many of these exceptions appear in the _BufferChannelFile_ class in the _size()_ method because the call to _file.channel()_ return null.
> My question is then, is _NodeTableNative___ even the right place to implement this optimization, and second, if it is the right place to implement, can you help me understand why this exception is thrown?



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