Pig 诊断操作符 Pig存储数据 Pig描述操作符 该 负载 语句将简单地将数据加载到Apache的pig指定的关系。要验证 Load 语句的执行情况，必须使用 诊断操作符 。pig拉丁文提供了四种不同类型的诊断操作符 - 转储运营商 描述操作符 解释运算符 插图运算符 在本章中，我们将讨论Pig Latin的转储操作符。 转储运营商 转 储运 算符用于运行Pig Latin语句并在屏幕上显示结果。它通常用于调试目的。 句法 下面给出了 转储 操作符的语法。 grunt> Dump Relation_Name 例 假设我们在HDFS中具有以下内容的文件 student_data.txt 。 001,Rajiv,Reddy,9848022337,Hyderabad 002,siddarth,Battacharya,9848022338,Kolkata 003,Rajesh,Khanna,9848022339,Delhi 004,Preethi,Agarwal,9848022330,Pune 005,Trupthi,Mohanthy,9848022336,Bhuwaneshwar 006,Archana,Mishra,9848022335,Chennai. 我们已经使用LOAD运算符将其读入关系 学生 ，如下所示。 grunt> student = LOAD 'hdfs://localhost:9000/pig_data/student_data.txt' USING PigStorage(',') as ( id:int, firstname:chararray, lastname:chararray, phone:chararray, city:chararray ); 现在，让我们使用转 储运算符 打印关系的内容，如下所示。 grunt> Dump student 一旦你执行上面的 Pig Latin 语句，它将启动一个MapReduce作业从HDFS读取数据。它会产生以下输出。 2015-10-01 15:05:27,642 [main] INFO org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher - 100% complete 2015-10-01 15:05:27,652 [main] INFO org.apache.pig.tools.pigstats.mapreduce.SimplePigStats - Script Statistics: HadoopVersion PigVersion UserId StartedAt FinishedAt Features 2.6.0 0.15.0 Hadoop 2015-10-01 15:03:11 2015-10-01 05:27 UNKNOWN Success! Job Stats (time in seconds): JobId job_14459_0004 Maps 1 Reduces 0 MaxMapTime n/a MinMapTime n/a AvgMapTime n/a MedianMapTime n/a MaxReduceTime 0 MinReduceTime 0 AvgReduceTime 0 MedianReducetime 0 Alias student Feature MAP_ONLY Outputs hdfs://localhost:9000/tmp/temp580182027/tmp757878456, Input(s): Successfully read 0 records from: "hdfs://localhost:9000/pig_data/ student_data.txt" Output(s): Successfully stored 0 records in: "hdfs://localhost:9000/tmp/temp580182027/ tmp757878456" Counters: Total records written : 0 Total bytes written : 0 Spillable Memory Manager spill count : 0Total bags proactively spilled: 0 Total records proactively spilled: 0 Job DAG: job_1443519499159_0004 2015-10-01 15:06:28,403 [main] INFO org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLau ncher - Success! 2015-10-01 15:06:28,441 [main] INFO org.apache.pig.data.SchemaTupleBackend - Key [pig.schematuple] was not set... will not generate code. 2015-10-01 15:06:28,485 [main] INFO org.apache.hadoop.mapreduce.lib.input.FileInputFormat - Total input paths to process : 1 2015-10-01 15:06:28,485 [main] INFO org.apache.pig.backend.hadoop.executionengine.util.MapRedUtil - Total input paths to process : 1 **(1,Rajiv,Reddy,9848022337,Hyderabad) (2,siddarth,Battacharya,9848022338,Kolkata) (3,Rajesh,Khanna,9848022339,Delhi) (4,Preethi,Agarwal,9848022330,Pune) (5,Trupthi,Mohanthy,9848022336,Bhuwaneshwar) (6,Archana,Mishra,9848022335,Chennai)** Pig存储数据 Pig描述操作符
