Hive扩展功能(九)--Hive的行级更新操作(Update)

软件环境:

linux系统: CentOS6.7

Hadoop版本: 2.6.5

zookeeper版本: 3.4.8

##主机配置:
####一共m1, m2, m3这三部机, 每部主机的用户名都为centos
```
192.168.179.201: m1
192.168.179.202: m2
192.168.179.203: m3

m1: Zookeeper, Namenode, DataNode, ResourceManager, NodeManager, Master, Worker

m2: Zookeeper, Namenode, DataNode, ResourceManager, NodeManager, Worker

m3: Zookeeper, DataNode, NodeManager, Worker

####资料:

官方资料:

Update资料 <=> https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML

Join资料 <=> https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Joins

网上参考资料:

Update资料 <=> http://www.aboutyun.com/thread-12155-1-1.html

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##一.为Hive配置Update功能

####1.编辑hive-site.xml文件:

hive.optimize.sort.dynamic.partition
false

hive.support.concurrency
true

hive.enforce.bucketing
true

hive.exec.dynamic.partition.mode
nonstrict

hive.txn.manager
org.apache.hadoop.hive.ql.lockmgr.DbTxnManager

hive.compactor.initiator.on
true

hive.compactor.worker.threads
1

hive.in.test
true

```

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##二.Update语法
####1.创表语句
Hive对使用Update功能的表有特定的语法要求, 语法要求如下:
(1)要执行Update的表中, 建表时必须带有buckets(分桶)属性
(2)要执行Update的表中, 需要指定格式,其余格式目前赞不支持, 如:parquet格式, 目前只支持ORCFileformat和AcidOutputFormat
(3)要执行Update的表中, 建表时必须指定参数('transactional' = true);
举例:
```
create table student (id bigint,name string) clustered by (name) into 2 buckets stored as orc TBLPROPERTIES('transactional'='true');
```

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2.更新语句:

update student set id='444' where name='tom';

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