Hive与Oracle表关联语句对比

在将Oracle存储过程迁移到HIVE平台时，不可避免地会遇到表关联的相应语法问题。本文详细对比了ORALCE和HIVE的各种表关联语法，包括内关联，左，右关联，全外关联和笛卡尔积。一.创建表ORACLE：create table a
（
a1 number（10）,
a2 varchar2（50）
）;create table b
（
b1 number（10）,
b2 varchar2（50）
）;HIVE：CREATE TABLE IF NOT EXISTS a （
a1 STRING,
a2 STRING）
COMMENT "TABLE A"
ROW FORMAT DELIMITED
FIELDS TERMINATED BY "|"
LINES TERMINATED BY " "
STORED AS TEXTFILE
TBLPROPERTIES （ "created_at"="2014-04-28","creator"="HENRY" ）;二.插入数据ORACLE：insert into a（a1,a2） values（1,"X"）;
insert into a（a1,a2） values（2,"Y"）;
insert into a（a1,a2） values（3,"Z"）;insert into b（b1,b2） values（1,"X"）;
insert into b（b1,b2） values（2,"Y"）;
insert into b（b1,b2） values（4,"Z"）;HIVE：hive （default）> load data local inpath "./data1" into table a;
Copying data from file:/home/Hadoop/roger/sql/renguihe/data
Copying file: file:/home/hadoop/roger/sql/renguihe/data
Loading data to table default.a
Table default.a stats: [num_partitions: 0, num_files: 1, num_rows: 0, total_size: 12, raw_data_size: 0]
OK
Time taken: 1.961 seconds
hive （default）> load data local inpath "./data1" into table b;
Copying data from file:/home/hadoop/roger/sql/renguihe/data
Copying file: file:/home/hadoop/roger/sql/renguihe/data
Loading data to table default.b
Table default.b stats: [num_partitions: 0, num_files: 1, num_rows: 0, total_size: 12, raw_data_size: 0]
OK
Time taken: 0.392 seconds其中data1数据文件内容为：1|X
2|Y
3|Zdata2数据文件内容为：1|X
2|Y
4|Z三.等值关联ORACLE：select * from a,b where a.a1 = b.b1;或：select * from a join b on a.a1 = b.b1;结果如下图所示： HIVE：select * from a join b on a.a1 = b.b1;注意HIVE中不能使用where来表示关联条件。执行过程及结果如下图所示：hive （default）> select * from a join b on a.a1 = b.b1;
Total MapReduce jobs = 1
setting HADOOP_USER_NAME hadoop
Execution log at: /tmp/hadoop/.log
2014-04-29 09:13:27 Starting to launch local task to process map join; maximum memory = 1908932608
2014-04-29 09:13:27 Processing rows: 3 Hashtable size: 3 Memory usage: 110981704 rate: 0.058
2014-04-29 09:13:27 Dump the hashtable into file: file:/tmp/hadoop/hive_2014-04-29_09-13-25_273_8486588204512196396/-local-10002/HashTable-Stage-3/MapJoin-mapfile00--.hashtable
2014-04-29 09:13:27 Upload 1 File to: file:/tmp/hadoop/hive_2014-04-29_09-13-25_273_8486588204512196396/-local-10002/HashTable-Stage-3/MapJoin-mapfile00--.hashtable File size: 438
2014-04-29 09:13:27 End of local task; Time Taken: 0.339 sec.
Execution completed successfully
Mapred Local Task Succeeded . Convert the Join into MapJoin
Mapred Local Task Succeeded . Convert the Join into MapJoin
Launching Job 1 out of 1
Number of reduce tasks is set to 0 since there"s no reduce operator
Starting Job = job_201404251509_0131, Tracking URL = <a href="http://IP:50030/jobdetails.jsp？jobid=job_201404251509_0131Kill" target="_blank">http://<span style="color: rgb（0, 0, 0）;">IP</span>:50030/jobdetails.jsp？jobid=job_201404251509_0131
Kill</a> Command = /home/hadoop/package/hadoop-1.0.4/libexec/../bin/hadoop job -kill job_201404251509_0131
Hadoop job information for Stage-3: number of mappers: 1; number of reducers: 0
2014-04-29 09:13:39,979 Stage-3 map = 0%, reduce = 0%
2014-04-29 09:13:46,025 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:47,034 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:48,044 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:49,052 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:50,061 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:51,069 Stage-3 map = 100%, reduce = 0%, Cumulative CPU 1.59 sec
2014-04-29 09:13:52,077 Stage-3 map = 100%, reduce = 100%, Cumulative CPU 1.59 sec
MapReduce Total cumulative CPU time: 1 seconds 590 msec
Ended Job = job_201404251509_0131
MapReduce Jobs Launched:
Job 0: Map: 1 Cumulative CPU: 1.59 sec HDFS Read: 211 HDFS Write: 16 SUCCESS
Total MapReduce CPU Time Spent: 1 seconds 590 msec
OK
a1 a2 b1 b2
1 X 1 X
2 Y 2 Y更多详情见请继续阅读下一页的精彩内容： http://www.linuxidc.com/Linux/2014-04/100999p2.htm

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