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

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-5906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13745075#comment-13745075 ] 

Jonathan Ellis commented on CASSANDRA-5906:
-------------------------------------------

I see two options:

# Build the BF [from the index] after the rest of compaction is complete and we know how many partitions need to be accounted for post-merge.
# Use merge statistics (CASSANDRA-5078) to make a better estimate
                
> 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
>            Priority: Minor
>             Fix For: 2.0.1
>
>
> 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.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira