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https://issues.apache.org/jira/browse/LUCENE-9480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17287732#comment-17287732
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Robert Muir commented on LUCENE-9480:
-------------------------------------
Thanks [~gsmiller], I like the patch: it makes it totally clear where the
bad/wasteful implementations are! (ByteBuffersDataInput,
CompressingStoredFieldsReader, ByteSliceReader etc).
We can followup with other patches to speed those bad guys up, some of them are
important, some are also the ones likely responsible for the useless
undesirable garbage that you want to fix.
> 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, 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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