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https://issues.apache.org/jira/browse/CASSANDRA-9323?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis resolved CASSANDRA-9323.
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Resolution: Won't Fix
Fix Version/s: (was: 2.1.x)
The preferred way to bulk load is now COPY; see CASSANDRA-11053 and linked
tickets.
> Bulk loading is slow
> --------------------
>
> Key: CASSANDRA-9323
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9323
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Pierre N.
> Attachments: App.java
>
>
> When I bulk upload sstable created with CQLSSTableWriter, it's very slow. I
> tested on a fresh cassandra node (nothing in keyspace, nor tables) with good
> hardware (8x2.8ghz, 32G ram), but with classic hard disk (performance won't
> be improved with SSD in this case I think).
> When I upload from a different server an sstable using sstableloader I get an
> average of 3 MB/sec, in the attached example I managed to get 5 MB/sec, which
> is still slow.
> During the streaming process I noticed that one core of the server is full
> CPU, so I think the operation is CPU bound server side. I quickly attached a
> sample profiler to the cassandra instance and got the following output :
> https://i.imgur.com/IfLc2Ip.png
> So, I think, but I may be wrong because it's inaccurate sampling, during
> streaming the table is unserialized and reserialized to another sstable, and
> that's this unserialize/serialize process which is taking a big amount of
> CPU, slowing down the insert speed.
> Can someone confirm the bulk load is slow ? I tested also on my computer and
> barely reach 1MB/sec
> I don't understand the point of totally unserializing the table I just did
> build using the CQLSStableWriter (because it's already a long process to
> build and sort the table), couldn't it just copy the table from offset X to
> offset Y (using index information by example) without
> unserializing/reserializing it ?
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