Question

Hello I m trying to obtain data from cassandra using hector. There are two ways of doing this.

a) 类似情况:

CqlQuery<String, String, Long> cqlQuery = new CqlQuery<String, String, Long>(connect.tutorialKeyspace, stringSerializer, stringSerializer, longSerializer);
    cqlQuery.setQuery("select home from page_view_counts where KEY ="localhost");

    QueryResult<CqlRows<String, String, Long>> result;
    try
    {
        result = cqlQuery.execute();
    }
    catch(HectorException e){
        result = null;
        message = e.getMessage();
    }

如果没有问询,它就应当如此,但我可以不问:

SliceQuery<String, String, Long> query = HFactory.createSliceQuery(connect.tutorialKeyspace, stringSerializer,stringSerializer,longSerializer); 
    QueryResult<ColumnSlice<String, Long>> result2 = query.setColumnFamily("page_view_counts").setKey("localhost").setColumnNames("home").execute();

我在什么地方犯错误?

Answer 1

你的例子不完整,你没有说明失败之处。但是,从研究你的法典来看,有几处错误:错误的类型、论点,你需要使用具体的反常类型,如果只读一栏,就不需要Slice。这一榜样应当发挥作用:

CounterQuery<String, String> query = HFactory.createCounterColumnQuery(keyspace, stringSerializer,stringSerializer);
query.setColumnFamily("page_view_counts").setKey("localhost").setName("home");
HCounterColumn<String> counter = query.execute().get();
System.out.println("Count:" + counter.getValue());

If you do need a Slice, then the result returned from HFactory.createSliceCounterSliceQuery() will be

QueryResult<CounterSlice<String>>

which will contain the List of

HCounterColumn<String>

Answer 2

Using the ColumnFamilyTemplate API might be the best way to get started easily. See: http://rantav.github.com/hector/build/html/content/getting_started.html (part or hector-client.org mentioned above).

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