[jira] [Updated] (CASSANDRA-15511) Utilising BTree Improvements

["Benedict Elliott Smith (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-15511?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benedict Elliott Smith updated CASSANDRA-15511:
-----------------------------------------------
    Change Category: Performance
         Complexity: Normal
           Assignee: Benedict Elliott Smith
             Status: Open  (was: Triage Needed)

> Utilising BTree Improvements
> ----------------------------
>
>                 Key: CASSANDRA-15511
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15511
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Local/Other
>            Reporter: Benedict Elliott Smith
>            Assignee: Benedict Elliott Smith
>            Priority: Normal
>
> This patch utilises CASSANDRA-15510 to improve throughput and reduce garbage produced by a number of common operations, by employing {{transformAndFilter}}, {{transform}} and {{FastBuilder}}
> {{Row}}, {{Cell}} and {{ComplexColumnData}} cloning are implemented with {{BTree.transform}}, so no special builders are necessary; {{Rows.copy}} removed
> {{Rows.merge}} implemented using {{BTree.update}} and a {{ColumnData}} reconciler
> Zero-allocations if result of merge is same as {{existing}}
> Fewer comparisons
> {{ColumnData}} reconciler implemented in same manner
> {{Cells.reconcileComplex}} is retired
> {{ComplexColumnData}} reconciliation now
> Garbage-free if the merge has no effect
> Always fewer allocations
> Fewer comparisons
> {{FastBuilder}} employed widely:
> {{ClusteringIndexNamesFilter}} deserialization
> {{Columns}} deserialization
> {{PartitionUpdate}} deserialization
> {{AbstractBTreePartition}} construction
> Misc others
> The upshot of this work when combined with the proposed patch for CASSANDRA-15367 has a dramatic impact on operations over collection types - under contention, as much as 100x improved throughput, and hundreds of megabytes of reduced allocations.  For all operations, allocations under contention and no contention are significantly reduced and throughput improved.
> I am still awaiting the final results of the comprehensive performance comparison for {{AtomicBTreePartition}}, after which I will establish what impact there might be on compaction and normal reads, both of which should be affected by this patch.



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