如何从 cassandra 和 hector 中获取反列的值？

发布于 2024-12-13 03:42:16 字数 965 浏览 0 评论 0原文

您好，我正在尝试使用 hector 从 cassandra 获取数据。有两种方法可以做到这一点。

一个是像这样的 cqlQuery：

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();
    }

如果没有查询，它应该是这样的，但我无法让它工作：

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();

我在哪里犯了错误？

原文

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

one is with a cqlQuery like this:

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();
    }

And without queries it should be something like this, but I can't get it to work:

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();

Where do I make the mistake?

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亣腦蒛氧 2024-12-20 03:42:16

你的例子不完整，你没有指出什么是失败的。但从你的代码来看，有一些错误：类型、参数不正确，你需要使用特定的 Counter 类型，如果只是获取单个列，则不需要 Slice。这个例子应该有效：

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());

如果您确实需要一个 Slice，那么从 HFactory.createSliceCounterSliceQuery() 返回的结果将

QueryResult<CounterSlice<String>>

包含以下列表：

HCounterColumn<String>

Your examples are incomplete, you give no indication of what is failing. But from looking at your code, there are a few things wrong: incorrect types, arguments, you need to use specific Counter types, and if just getting a single column then don't need Slice. This example should work:

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