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https://issues.apache.org/jira/browse/CASSANDRA-9989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587507#comment-16587507
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Benedict commented on CASSANDRA-9989:
-------------------------------------
Thanks Jay. The patch looks good overall, but I have few improvement comments,
and some questions:
# How did you arrive at your {{childrenNum}} calculation, and are we certain it
is correct? This is pretty critical for correctness, and hard to test fully,
so it would be nice to have some comments justifying it.
# Why decrement {{left}} instead of just counting up the number of values
written?
# Why is TREE_SIZE indexed from 1, not 0?
# It would be nice if we removed MAX_DEPTH, and just truncated TREE_SIZE to the
correct maximum in our static block
I'm also torn on the splitting of the last two nodes - this is consistent with
the current {{NodeBuilder}} logic, but it does complicate the code a little
versus evenly splitting the remaining size amongst all the children.
I've pushed a patch
[here|https://github.com/belliottsmith/cassandra/tree/9989-suggest] with some
tweaks to the {{LongBTreeTest}} to stress the new code paths more more, and it
would be great if we could run this against the final patch for a while, with a
tweak to the parameters to increase further the ratio of tests that use this
code path.
> Optimise BTree.Buider
> ---------------------
>
> Key: CASSANDRA-9989
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9989
> Project: Cassandra
> Issue Type: Sub-task
> Reporter: Benedict
> Assignee: Jay Zhuang
> Priority: Minor
> Fix For: 4.x
>
> Attachments: 9989-trunk.txt
>
>
> BTree.Builder could reduce its copying, and exploit toArray more efficiently,
> with some work. It's not very important right now because we don't make as
> much use of its bulk-add methods as we otherwise might, however over time
> this work will become more useful.
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