Thanks for the hint.
I found out it was "too many opened files" error and the server side
just lost response to the get_range_slice() request by throwing out an
exception.
Now works with "ulimit -n 32768".
Kevin
-------- ???????? --------
??????: Jonathan Ellis <jbel...@gmail.com>
??????: user@cassandra.apache.org
????: [***SPAM*** ] Re: problem when trying to get_range_slice()
????: Thu, 3 Jun 2010 19:07:28 -0700
use smaller slices and page through the data
2010/6/3 Shuai Yuan <yuansh...@supertool.net.cn>:
> Hi all,
>
> ----my env----
>
> 6 servers with about 200GB data.
>
> data structure,
>
> 64B rowkey + (5B column)*20,
> rowkey and column.value are all random bytes from a-z,A-Z,0-9
>
> ----problem----
>
> when I tried iterate over the data in the storage, I always get
> org::apache::cassandra::TimedOutException
> (RpcTimeout = 2minutes)
>
> ----questions----
>
> 1.How could I iterate over my data then?
>
> 2.In the code below, I gave key_start/end/count twice, one for
> get_range_slice() and the other for SlicePreditor. Are they the same?
>
> Thanks!
>
> ----scan-data application----
>
> CassandraFactory factory(argv[1], 9160);
> tr1::shared_ptr<Cassandra> client(factory.create());
>
> Keyspace *key_space = client->getKeyspace("campaign");
>
> map<string, vector<Column> > mResult;
> ColumnParent cp;
> SlicePredicate sp;
> string szStart, szEnd;
> uint32_t uCount = 100; //try to retrieve 100 keys?
>
> szStart =
> "0000000000000000000000000000000000000000000000000000000000000000";
> szEnd =
> "1000000000000000000000000000000000000000000000000000000000000000";
>
> cp.column_family = "test_col";
>
> sp.__isset.slice_range = true;
> sp.slice_range.start =
> "0000000000000000000000000000000000000000000000000000000000000000";
> sp.slice_range.finish =
> "1000000000000000000000000000000000000000000000000000000000000000";
> sp.slice_range.count = 100;
>
> try {
> mResult = key_space->getRangeSlice(cp, sp, szStart, szEnd,
> uCount); //by libcassandra, mainly invoking get_range_slice()
>
> /* then iterate the result and output */
> }
> }
> } catch (org::apache::cassandra::InvalidRequestException &ire) {
> cout << ire.why << endl;
> delete key_space;
> return 1;
> }
>
> return 0;
> --
> Kevin Yuan
> www.yuan-shuai.info
>
>
>
