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From Caribbean410 <caribbean...@gmail.com>
Subject read operation is slow
Date Thu, 10 Jun 2010 21:39:24 GMT
Hello,

I am testing the performance of cassandra. We write 200k records to
database and each record is 1k size. Then we read these 200k records.
It takes more than 400s to finish the read which is much slower than
mysql (20s around). I read some discussion online and someone suggest
to make multiple connections to make it faster. But I am not sure how
to do it, do I need to change my storage setting file or just change
the java client code?

Here is my read code,

                    Properties info = new Properties();
                    info.put(DriverManager.CONSISTENCY_LEVEL,
                              ConsistencyLevel.ONE.toString());

                    IConnection connection = DriverManager.getConnection(
                                "thrift://localhost:9160", info);

                      // 2. Get a KeySpace by name
                      IKeySpace keySpace =
connection.getKeySpace("Keyspace1");

                      // 3. Get a ColumnFamily by name
                      IColumnFamily cf =
keySpace.getColumnFamily("Standard2");

                      ByteArray nameFirst = ByteArray.ofASCII("first");
                      ICriteria criteria = cf.createCriteria();
                      long readBytes = 0;
                      long start = System.currentTimeMillis();
                          for (int i = 0; i < numOfRecords; i++) {
                                  int n = random.nextInt(numOfRecords);
                                      userName = keySet[n];

criteria.keyList(Lists.newArrayList(userName)).columnRange(nameFirst,
nameFirst, 10);
                                      Map<String, List<IColumn>> map =
criteria.select();
                                      List<IColumn> list =
map.get(userName);
                                      ByteArray bloc =
list.get(0).getValue();
                                      byte[] byteArrayloc =
bloc.toByteArray();
                                      loc = new String(byteArrayloc);
//                                    System.out.println(userName+"
"+loc);
                                      readBytes = readBytes + loc.length();
                          }

                        long finish=System.currentTimeMillis();

I once commented these lines

                                      ByteArray bloc =
list.get(0).getValue();
                                      byte[] byteArrayloc =
bloc.toByteArray();
                                      loc = new String(byteArrayloc);
//                                    System.out.println(userName+"
"+loc);
                                      readBytes = readBytes + loc.length();

And the performance doesn't improve much.

Any suggestion is welcome. Thanks,

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