format_datetime(current_date, 'YYYY-MM-dd'),
format_datetime(DATE_ADD('day', -1, current_date), 'YYYY-MM-dd')
format_datetime(DATE_ADD('day', -2, current_date), 'YYYY-MM-dd')
[......]
Presto获取当天、昨天的格式化日期字符串
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Category Archives: 大数据技术
定制Hadoop的MapReduce任务的FileOutputFormat
需求：Reduce输出特殊的格式结果
例如：如Reducer的结果，压到Guava的BloomFilter中
import com.google.common.hash.BloomFilter;
import com.google.common.hash.Funnels;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.h[......]
Hadoop如何快速完成数值排序的工作
转载自：http://stackoverflow.com/questions/13331722/how-to-sort-numerically-in-hadoops-shuffle-sort-phase
Assuming you are using Hadoop Streaming, you need to use the KeyFieldBasedComparator class.
- -D mapred.output.key.comparator.class=org.apach[......]
Writing Hive Custom Aggregate Functions (UDAF)
转载自：《Writing Hive Custom Aggregate Functions (UDAF): Part II》
Now that we got eclipse configured (see Part I) for UDAF development, its time to write our first UDAF. Searching for custom UDAF, most people might have already came across the followi[......]
Hive自定义UDF/UDAF/UDTF中，如何获得List的ObjectInspector
在Hive中，在使用GenercU**F实现自定义UDF/UDAF/UDTF时，经常要制定输出类型，其中要获得一个ObjectInspector。
对于基础类型：
PrimitiveObjectInspectorFactory.javaStringObjectInspector)
对于List等复合类型，要2步：
ObjectInspectorFactory
.getStandardListObjectInspector(PrimitiveObjectInspectorFa[......]