在將ORACLE存儲過程遷移到HIVE平臺時，不可避免地會遇到表關聯的相應語法問題。本文詳細對比了ORALCE和HIVE的各種表關聯語法，包

在將Oracle存儲過程遷移到HIVE平臺時，不可避免地會遇到表關聯的相應語法問題。

本文詳細對比了ORALCE和HIVE的各種表關聯語法，，包括內關聯，左，右關聯，全外關聯和笛卡爾積。

一.創建表

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 '\n'

STORED AS TEXTFILE

TBLPROPERTIES ( 'created_at'='2014-04-28','creator'='HENRY' );

二.插入數據

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數據文件內容為：

1|X

2|Y

3|Z

data2數據文件內容為：

1|X

2|Y

4|Z

三.等值關聯

ORACLE：

select * from a,b where a.a1 = b.b1;

或：

select * from a join b on a.a1 = b.b1;

結果如下圖所示：

HIVE：

select * from a join b on a.a1 = b.b1;

注意HIVE中不能使用where來表示關聯條件。

執行過程及結果如下圖所示：

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 = IP:50030/jobdetails.jsp?jobid=job_201404251509_0131

Kill 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

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