import java.util.Comparator;
import java.util.List;
import java.util.stream.Collector;
import org.junit.Test;
import com.google.common.collect.Comparators;
import com.google.common.collect.Lists;
public class TestComparator {
@Test[......]
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collector;
import org.junit.Test;
import com.google.common.collect.Comparators;
import com.google.common.collect.Lists;
public class TestComparator {
@Test[......]
RT,在Hive中,使用了Group By后,是无法再sort,再取Top K的,我们可以用UDF + distributed by + sort by 实现这个功能。
参考自:EXTRACT TOP N RECORDS IN EACH GROUP IN HADOOP/HIVE
Assume you have a table with three columns: user, category and value. For each user, you want to select[......]