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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Java-Client returns empty data sets after Cassandra sits for a while
Date Sat, 19 Jun 2010 03:27:31 GMT
I can't think of any scenario where leaving Cassandra idle would
affect the results returned.  I think something else is going on here.

On Fri, Jun 18, 2010 at 2:05 AM, Manfred Muench
<docmanni@domainerschoice.com> wrote:
> Hi,
>
> I have noticed the following behaviour (bug?) which I don't completely
> understand:
> 1. start Cassandra (I'm using 0.6.2, but it also appears in 0.6.1)
> 2. work with it (I'm using Java thrift API)
> 3. let it sit for a long time (in my case: a day or more) without
> issuing any command
> 4. go back to (2) -- but now Cassandra always returns empty data sets to
> queries in Java. The command line interface works, no matter if left
> open or started newly.
>
> Here's how I connect to Cassandra (leaving exception handling out for better
> readability):
>
> ---------------------------------------------------------------------
> ...
> import org.apache.cassandra.thrift.Cassandra;
> import org.apache.thrift.protocol.TBinaryProtocol;
> import org.apache.thrift.protocol.TProtocol;
> import org.apache.thrift.transport.TSocket;
> ...
>
> TTransport transport = new TSocket(cassandraHost, cassandraPort);
> TProtocol protocol = new TBinaryProtocol(transport);
> Cassandra.Client client = new Cassandra.Client(protocol);
> transport.open();
> ...
> List<KeySlice> keySlices = client.get_range_slices(...);
> ...
> transport.flush();
> transport.close();
> ...
> ---------------------------------------------------------------------
>
> This code usually works, but after leaving Cassandra running unused for a
> couple of hours (days), this code connects fine to Cassandra, but the
> client.get_range_slices returns an empty result set.
>
> I am not very sure, but I believe it happens after compacting. Need to do
> more tests on this one.
>
> Does anybody know what I'm doing wrong here? Is there any kind of
> "initialisation step" that I should have taken before running queries?
>
> If you need more (debug) information on this matter, please let me know how
> I can provide you with it. The log files didn't show anything while running
> the query. The last log message was:
>
>  INFO [COMPACTION-POOL:1] 2010-06-18 14:07:45,882 CompactionManager.java
> (line 246) Compacting []
>
> I ran the query at around 14:20, no other message after this one.
>
> Thanks for your help in advance!
>
> Cheers,
> Manfred
>
> --
> Dr. Manfred Muench
> Nanjing Imperiosus Technology Co. Ltd.
> Wu Xing Nian Hua Da Sha, Room 1004
> 134 Hanzhong Lu, Nanjing, P.R. China
>
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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