从Cassandra ResultSet获取BigInteger属性

Question

我正在尝试获取Cassandra列族中的键值对的数量.以下是我使用的代码.

PreparedStatement statement = client.session
            .prepare("select count(*) from corpus.word_usage");
ResultSet results = client.session.execute(statement.bind());   
Row row = results.one();
System.out.println(row.getVarint(0));

但是,当我运行此代码时,我遇到了异常.

Exception in thread "main" com.datastax.driver.core.exceptions.InvalidTypeException: Column count is of type bigint
   at com.datastax.driver.core.ColumnDefinitions.checkType(ColumnDefinitions.java:291)
   at com.datastax.driver.core.ArrayBackedRow.getVarint(ArrayBackedRow.java:185)
   at SimpleClient.main(SimpleClient.java:57)

根据datastax文档(http://www.datastax.com/drivers/java/2.0/com/datastax/driver/core/Row.html),getVarint应该返回一个BigInteger.那么为什么我在这里得到例外？我做错了什么？

Answer 1

作为指定在这里,你可以得到的值作为一个长期的,而不是.

我无法测试它,但你可以试试这个:

PreparedStatement statement = client.session.prepare("select count(*) from corpus.word_usage");
ResultSet results = client.session.execute(statement.bind());   
Row row = results.one();
long expected = row.getLong("count");