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罗祥
2019-04-29 17:43:05 +08:00
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notes/Hive常用DML操作.md
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@ -208,72 +208,77 @@ DELETE FROM tablename [WHERE expression]
### 4.2 示例
1. 首先需要更改`hive-site.xml`，添加如下配置，开启事务支持，配置完成后需要重启Hive服务。
**1. 修改配置**
```xml
<property>
<name>hive.support.concurrency</name>
<value>true</value>
</property>
<property>
<name>hive.enforce.bucketing</name>
<value>true</value>
</property>
<property>
<name>hive.exec.dynamic.partition.mode</name>
<value>nonstrict</value>
</property>
<property>
<name>hive.txn.manager</name>
<value>org.apache.hadoop.hive.ql.lockmgr.DbTxnManager</value>
</property>
<property>
<name>hive.compactor.initiator.on</name>
<value>true</value>
</property>
<property>
<name>hive.in.test</name>
<value>true</value>
</property>
```
首先需要更改`hive-site.xml`，添加如下配置，开启事务支持，配置完成后需要重启Hive服务。
2. 创建用于测试的事务表，建表时候指定属性`transactional = true`则代表该表是事务表。需要注意的是，按照[官方文档](https://cwiki.apache.org/confluence/display/Hive/Hive+Transactions)的说明，目前Hive中的事务表有以下限制：
+ 必须是buckets Table;
+ 仅支持ORC文件格式；
+ 不支持LOAD DATA ...语句。
```sql
-- 建表语句
CREATE TABLE emp_ts(
empno int,
ename String
)
CLUSTERED BY (empno) INTO 2 BUCKETS STORED AS ORC
TBLPROPERTIES ("transactional"="true");
```
3. 插入测试数据
```sql
INSERT INTO TABLE emp_ts VALUES (1,"ming"),(2,"hong");
```
```xml
<property>
<name>hive.support.concurrency</name>
<value>true</value>
</property>
<property>
<name>hive.enforce.bucketing</name>
<value>true</value>
</property>
<property>
<name>hive.exec.dynamic.partition.mode</name>
<value>nonstrict</value>
</property>
<property>
<name>hive.txn.manager</name>
<value>org.apache.hadoop.hive.ql.lockmgr.DbTxnManager</value>
</property>
<property>
<name>hive.compactor.initiator.on</name>
<value>true</value>
</property>
<property>
<name>hive.in.test</name>
<value>true</value>
</property>
```
插入数据依靠的是MapReduce作业，执行成功后数据如下：
**2. 创建测试表**
<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-emp-ts.png"/> </div>
4. 测试更新和删除
```sql
--更新数据
UPDATE emp_ts SET ename = "lan" WHERE empno=1;
--删除数据
DELETE FROM emp_ts WHERE empno=2;
```
更新和删除数据依靠的也是MapReduce作业，执行成功后数据如下：
<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-emp-ts-2.png"/> </div>
创建用于测试的事务表，建表时候指定属性`transactional = true`则代表该表是事务表。需要注意的是，按照[官方文档](https://cwiki.apache.org/confluence/display/Hive/Hive+Transactions)的说明，目前Hive中的事务表有以下限制：
+ 必须是buckets Table;
+ 仅支持ORC文件格式；
+ 不支持LOAD DATA ...语句。
```sql
CREATE TABLE emp_ts(
empno int,
ename String
)
CLUSTERED BY (empno) INTO 2 BUCKETS STORED AS ORC
TBLPROPERTIES ("transactional"="true");
```
**3. 插入测试数据**
```sql
INSERT INTO TABLE emp_ts VALUES (1,"ming"),(2,"hong");
```
插入数据依靠的是MapReduce作业，执行成功后数据如下：
<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-emp-ts.png"/> </div>
**4. 测试更新和删除**
```sql
--更新数据
UPDATE emp_ts SET ename = "lan" WHERE empno=1;
--删除数据
DELETE FROM emp_ts WHERE empno=2;
```
更新和删除数据依靠的也是MapReduce作业，执行成功后数据如下：
<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-emp-ts-2.png"/> </div>