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From Tobias Jungen <>
Subject Re: BinaryMemtable and collisions
Date Sat, 08 May 2010 04:29:17 GMT
> Yes. When you flush from BMT, its like any other SSTable. Cassandra will
> merge them through compaction.
That's good news, thanks for clarifying!

A few more related questions:

Are there any problems with issuing the flush command directly from code at
the end up a bulk insert? The BMT example mentions running nodetool, but
poking around the Cassandra source seems to indicate it should be doable

Also, in my BMT prototype I've noticed that the JVM won't exit after
completion, so I have to hard kill it (ctrl-c). A thread dump shows that
some of Cassandra's network threads are still open, keeping the JVM from
exiting. Some digging revealed that Cassandra isn't designed with a "clean"
shutdown in mind, so perhaps such behavior is expected. Still, it is a bit
unsettling since the cluster nodes log an error after I kill the client
node. Is calling StorageService.stopClient enough to ensure that any
client-side buffers are flushed and writes are completed?

Finally, the wiki page on BMT ( suggests using
StorageProxy, but the example in contrib does not. Under the hood, both
StorageProxy and the contrib example call MessagingService.sendOneWay. The
additional code in StorageProxy seems mostly related to the extra
bookkeeping associated with hinted handoff and waiting on write acks.
Perhaps that extra work may not be entirely necessary for a bulk load

That should be enough questions from me for a while. :)


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