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https://issues.apache.org/jira/browse/LUCENE-9480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17287494#comment-17287494
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Robert Muir commented on LUCENE-9480:
-------------------------------------
I just think it is better for some subclass to be forced to think about the
situation, rather than just extending the class and being slow by default.
Definitely want to force the programmer to think: "oh, skipBytes() is abstract,
how should i implement this? I see there is this slow implementation available,
I don't want to write things in a slow way..."
> investigate slow DataInput.skipBytes
> ------------------------------------
>
> Key: LUCENE-9480
> URL: https://issues.apache.org/jira/browse/LUCENE-9480
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Robert Muir
> Priority: Major
> Attachments: LUCENE-9480.patch, LUCENE-9480.patch
>
>
> Currently DataInput has skipBytes(), but IndexInput also adds seek().
> There isn't a clear reason about the differences in the two methods: why
> would you choose one over the other?
> It causes some performance issues: for example the default implementation
> actually reads bytes into a byte array and throws everything away. This is
> really silly for MMapDirectory: skipping bytes should only be a glorified
> {{+=}}.
> So when I look at latest LUCENE-9447 patch, I can't help but think a ton of
> waste is happening:
> * Maybe skipBytes() is only used because the stored fields compressor
> interface happens to take DataInput? Should it take IndexInput instead?
> * Should skipBytes() be overridden by MMapDirectory rather than delegating to
> super? doing real reads and byte array copies isn't free. It should be a
> {{+=}} with single bounds check.
> * Should we revisit having DataInput vs IndexInput at all? Maybe they should
> be collapsed into one thing?
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