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https://issues.apache.org/jira/browse/CASSANDRA-9988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16105981#comment-16105981
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Jay Zhuang commented on CASSANDRA-9988:
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Hi [~benedict], would you please point me the exponential search implementation
for the branch iterator?
I tried to improve the
[expSearch|https://github.com/cooldoger/cassandra/commit/a23a3422a894acb72a47975da035bbf8da50fc4b],
here is [the improved
version|https://github.com/cooldoger/cassandra/commit/7330646e553afd4b4b0011f6163bf9032f9cb605]
which will do 1 comparison if it finds the target at the first stage. But
that's optimized to find the target on {{2^i}} position, doesn't cover position
0. To cover position 0 (the first element), I need to add more checks and code,
it makes the code hard to understand.
And if we really do that, I could have the same optimization for binarySearch
(manually check the first 1 or 2 elements), which results in the similar
improvement.
> Introduce leaf-only iterator
> ----------------------------
>
> Key: CASSANDRA-9988
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9988
> Project: Cassandra
> Issue Type: Sub-task
> Reporter: Benedict
> Assignee: Jay Zhuang
> Priority: Minor
> Labels: patch
> Fix For: 4.0
>
> Attachments: 9988-data.png, 9988-result2.png, 9988-result3.png,
> 9988-result.png, 9988-test-result3.png, 9988-test-result-expsearch.xlsx,
> 9988-test-result-raw.png, 9988-test-result.xlsx, 9988-trunk-new.txt,
> 9988-trunk-new-update.txt, trunk-9988.txt
>
>
> In many cases we have small btrees, small enough to fit in a single leaf
> page. In this case it _may_ be more efficient to specialise our iterator.
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