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From "Peter Schuller (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3943) Too many small size sstables after loading data using sstableloader or BulkOutputFormat increases compaction time.
Date Thu, 22 Mar 2012 08:12:26 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13235440#comment-13235440
] 

Peter Schuller commented on CASSANDRA-3943:
-------------------------------------------

It also facilitates replacing a data set one sstable at a time (if one generates sstables
that correspond exactly in ranges), allowing completely replacement of a dataset without a
temporary disk space spike.

Without any of these fixes, extra disk space needed is very significant - both regular compaction
overhead in addition to loading two data sets onto the node.
                
> Too many small size sstables after loading data using sstableloader or BulkOutputFormat
increases compaction time.
> ------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-3943
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3943
>             Project: Cassandra
>          Issue Type: Wish
>          Components: Hadoop, Tools
>    Affects Versions: 0.8.2, 1.1.0
>            Reporter: Samarth Gahire
>            Priority: Minor
>              Labels: bulkloader, hadoop, ponies, sstableloader, streaming, tools
>   Original Estimate: 168h
>  Remaining Estimate: 168h
>
> When we create sstables using SimpleUnsortedWriter or BulkOutputFormat,the size of sstables
created is around the buffer size provided.
> But After loading , sstables created in the cluster nodes are of size around
> {code}( (sstable_size_before_loading) * replication_factor ) / No_Of_Nodes_In_Cluster{code}
> As the no of nodes in cluster goes increasing, size of each sstable loaded to cassandra
node decreases.Such small size sstables take too much time to compact (minor compaction) as
compare to relatively large size sstables.
> One solution that we have tried is to increase the buffer size while generating sstables.But
as we increase the buffer size ,time taken to generate sstables increases.Is there any solution
to this in existing versions or are you fixing this in future version?

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