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https://issues.apache.org/jira/browse/CASSANDRA-15393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17175221#comment-17175221
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Caleb Rackliffe commented on CASSANDRA-15393:
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In terms of the higher level question of whether a change like this belongs in
4.0, I'm generally of the opinion that it does, given that it benefits both
compaction and local reads. There are things to clean up, but once that
happens, it really should be pretty hard to make the kind of errors mentioned
[above|https://issues.apache.org/jira/browse/CASSANDRA-15393?focusedCommentId=17173009&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-17173009].
If I were arguing against including this in 4.0, I would probably point to the
sheer size of the patch and the amount of typing information it adds to
existing classes, although the new type information on classes and method
signatures means the number of lines in the diff is kind of misleading as a
measure of how risky the change is.
Unless we think the patch will both hamper future efforts to avoid
materializing objects on heap in the first place during compaction, I don't see
a strong reason not to move forward.
> Add byte array backed cells
> ---------------------------
>
> Key: CASSANDRA-15393
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15393
> Project: Cassandra
> Issue Type: Sub-task
> Components: Local/Compaction
> Reporter: Blake Eggleston
> Assignee: Blake Eggleston
> Priority: Normal
> Fix For: 4.0-beta
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> We currently materialize all values as on heap byte buffers. Byte buffers
> have a fairly high overhead given how frequently they’re used, and on the
> compaction and local read path we don’t do anything that needs them. Use of
> byte buffer methods only happens on the coordinator. Using cells that are
> backed by byte arrays instead in these situations reduces compaction and read
> garbage up to 22% in many cases.
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