[jira] [Updated] (CASSANDRA-5906) Avoid allocating over-large bloom filters

["Yuki Morishita (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5906?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Yuki Morishita updated CASSANDRA-5906:
--------------------------------------

    Attachment: 5906.txt

(also: https://github.com/yukim/cassandra/tree/5906-v3)

Attaching patch for review.

* implemented on top of CASSANDRA-6356
* updated stream-lib to v2.5.1 (latest)

HLL++ parameters are p=13, sp=25 from my observation above.


> Avoid allocating over-large bloom filters
> -----------------------------------------
>
>                 Key: CASSANDRA-5906
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5906
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Yuki Morishita
>             Fix For: 2.1
>
>         Attachments: 5906.txt
>
>
> We conservatively estimate the number of partitions post-compaction to be the total number of partitions pre-compaction.  That is, we assume the worst-case scenario of no partition overlap at all.
> This can result in substantial memory wasted in sstables resulting from highly overlapping compactions.



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