大数据开发之Hive篇19-Hive分区表详解

红太狼 2023-01-07 01:25 169阅读 0赞

备注:  
Hive 版本 2.1.1

### 文章目录 ###

*  一.Hive分区表概述
 *  二.静态分区
 *   *  2.1 单分区测试
     *  2.2 多分区测试
 *  三.动态分区
 *   *  3.1 动态分区测试
     *  3.2 动态分区和静态分区混合使用
 *  四.分区的其它操作
 *   *  4.1 恢复分区
     *  4.2 归档分区
     *  4.3 交换分区
 *  参考

# 一.Hive分区表概述 #

数据分区的概念以及存在很久了，通常使用分区来水平分散压力，将数据从物理上移到和使用最频繁的用户更近的地方，以及实现其目的。 hive中有分区表的概念，我们可以看到分区具重要性能优势，而且分区表还可以将数据以一种符合逻辑的方式进行组织，比如分层存储

Hive官方网站对Hive partition的介绍:  
可以使用Partitioned BY子句创建分区表。一个表可以有一个或多个分区列，并且为分区列中的每个不同的值组合创建一个单独的数据目录。此外，可以使用按列聚集的方式对表或分区进行存储，并且可以通过按列排序的方式在存储区内对数据进行排序。这可以提高某些查询的性能。

如果在创建分区表时，出现这样的错误:“FAILED: error in semantic analysis: Column repeated in partitioning columns”，这意味着您试图将分区的列包含在表本身的数据中。您可能确实定义了列。但是，您创建的分区会生成一个可以查询的伪列，因此必须将表列重命名为其他东西(用户不应该查询的东西!)。

分区表分别有静态分区和动态分区

**创建分区表语法:**

CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name    -- (Note: TEMPORARY available in Hive 0.14.0 and later)
      [(col_name data_type [column_constraint_specification] [COMMENT col_comment], ... [constraint_specification])]
      [COMMENT table_comment]
      [PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]
      [CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]
      [SKEWED BY (col_name, col_name, ...)                  -- (Note: Available in Hive 0.10.0 and later)]
         ON ((col_value, col_value, ...), (col_value, col_value, ...), ...)
         [STORED AS DIRECTORIES]
      [
       [ROW FORMAT row_format] 
       [STORED AS file_format]
         | STORED BY 'storage.handler.class.name' [WITH SERDEPROPERTIES (...)]  -- (Note: Available in Hive 0.6.0 and later)
      ]
      [LOCATION hdfs_path]
      [TBLPROPERTIES (property_name=property_value, ...)]   -- (Note: Available in Hive 0.6.0 and later)
      [AS select_statement];   -- (Note: Available in Hive 0.5.0 and later; not supported for external tables)

**修改分区表语法:**  
通过在ALTER TABLE语句中使用PARTITION子句，可以添加、重命名、交换(移动)、删除或归档分区

-- 新增分区
    ALTER TABLE table_name ADD [IF NOT EXISTS] PARTITION partition_spec [LOCATION 'location'][, PARTITION partition_spec [LOCATION 'location'], ...];
     
    partition_spec:
      : (partition_column = partition_col_value, partition_column = partition_col_value, ...)
    
    -- 重命名分区
    ALTER TABLE table_name PARTITION partition_spec RENAME TO PARTITION partition_spec;
    
    -- 删除分区
    ALTER TABLE table_name DROP [IF EXISTS] PARTITION partition_spec;
    
    -- 删除分区(回收站不保留，直接删除)
    ALTER TABLE table_name DROP [IF EXISTS] PARTITION partition_spec PURGE;
    
    -- 归档和还原归档分区表
    ALTER TABLE table_name ARCHIVE PARTITION partition_spec;
    ALTER TABLE table_name UNARCHIVE PARTITION partition_spec;

# 二.静态分区 #

可以根据PARTITIONED BY创建分区表，一个表可以拥有一个或者多个分区，每个分区以文件夹的形式单独存在表文件夹的目录下。  
分区是以字段的形式在表结构中存在，通过describe table命令可以查看到字段存在，但是该字段不存放实际的数据内容，仅仅是分区的表示。  
分区建表分为2种，一种是单分区，也就是说在表文件夹目录下只有一级文件夹目录。另外一种是多分区，表文件夹下出现多文件夹嵌套模式。

## 2.1 单分区测试 ##

代码:

-- 创建分区表
    create table test_part(key int,value string) partitioned by (dt string);
    -- 查看分区表
    describe formatted test_part;
    -- 往分区表录入数据
    insert into test_part partition(dt = '2020-12-29') values (1,'abc');
    insert into test_part partition(dt = '2020-12-30') values (2,'def');
    insert into test_part partition(dt = '2020-12-31') values (3,'ghi');
    
    -- 新增分区
    alter table  test_part add partition(dt = '2021-01-01');
    -- 重命名分区
    alter table test_part partition(dt = '2021-01-01') rename to partition(dt = '2021-01-02');
    -- 删除分区
    alter table test_part drop partition(dt='2020-12-31');
    -- 删除分区(回收站不保留，直接删除)
    alter table test_part drop partition(dt='2020-12-30') purge;

测试记录:

hive> 
        > create table test_part(key int,value string) partitioned by (dt string);
    OK
    Time taken: 0.087 seconds
    hive> describe formatted test_part;
    OK
    # col_name              data_type               comment             
                     
    key                     int                                         
    value                   string                                      
                     
    # Partition Information          
    # col_name              data_type               comment             
                     
    dt                      string                                      
                     
    # Detailed Table Information             
    Database:               test                     
    OwnerType:              USER                     
    Owner:                  root                     
    CreateTime:             Tue Dec 29 15:59:02 CST 2020     
    LastAccessTime:         UNKNOWN                  
    Retention:              0                        
    Location:               hdfs://nameservice1/user/hive/warehouse/test.db/test_part        
    Table Type:             MANAGED_TABLE            
    Table Parameters:                
            COLUMN_STATS_ACCURATE   {\"BASIC_STATS\":\"true\"}
            numFiles                0                   
            numPartitions           0                   
            numRows                 0                   
            rawDataSize             0                   
            totalSize               0                   
            transient_lastDdlTime   1609228742          
                     
    # Storage Information            
    SerDe Library:          org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe       
    InputFormat:            org.apache.hadoop.mapred.TextInputFormat         
    OutputFormat:           org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat       
    Compressed:             No                       
    Num Buckets:            -1                       
    Bucket Columns:         []                       
    Sort Columns:           []                       
    Storage Desc Params:             
            serialization.format    1                   
    Time taken: 0.193 seconds, Fetched: 38 row(s)
    hive> 
    
    
    hive> insert into test_part partition(dt = '2020-12-29') values (1,'abc');
    Query ID = root_20201229160327_aef35dcf-1aaa-4b30-b47b-cbe9ea3aec3e
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:03:28 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0003, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0003/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0003
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:03:35,297 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:03:42,522 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 2.85 sec
    MapReduce Total cumulative CPU time: 2 seconds 850 msec
    Ended Job = job_1609141291605_0003
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part/dt=2020-12-29/.hive-staging_hive_2020-12-29_16-03-27_864_460539835119685808-1/-ext-10000
    Loading data to table test.test_part partition (dt=2020-12-29)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 2.85 sec   HDFS Read: 4229 HDFS Write: 90 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 2 seconds 850 msec
    OK
    Time taken: 16.389 seconds
    hive> 
        > insert into test_part partition(dt = '2020-12-30') values (2,'def');
    Query ID = root_20201229160421_9da78dee-ff03-4d5a-9fef-b3808a69a3c6
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:04:22 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0004, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0004/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0004
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:04:29,214 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:04:36,442 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 2.99 sec
    MapReduce Total cumulative CPU time: 2 seconds 990 msec
    Ended Job = job_1609141291605_0004
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part/dt=2020-12-30/.hive-staging_hive_2020-12-29_16-04-21_921_4429247941950558015-1/-ext-10000
    Loading data to table test.test_part partition (dt=2020-12-30)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 2.99 sec   HDFS Read: 4232 HDFS Write: 90 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 2 seconds 990 msec
    OK
    Time taken: 17.229 seconds
    hive> 
        > insert into test_part partition(dt = '2020-12-31') values (3,'ghi');
    Query ID = root_20201229160458_be37945d-a462-4ab1-b8fe-0180277c2399
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:04:58 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0005, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0005/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0005
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:05:06,866 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:05:13,062 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 3.03 sec
    MapReduce Total cumulative CPU time: 3 seconds 30 msec
    Ended Job = job_1609141291605_0005
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part/dt=2020-12-31/.hive-staging_hive_2020-12-29_16-04-58_612_6006646373659507783-1/-ext-10000
    Loading data to table test.test_part partition (dt=2020-12-31)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 3.03 sec   HDFS Read: 4232 HDFS Write: 90 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 3 seconds 30 msec
    OK
    Time taken: 16.151 seconds
    hive> 
        > alter table  test_part add partition(dt = '2021-01-01');
    OK
    Time taken: 0.147 seconds
    hive> 
        > alter table test_part partition(dt = '2021-01-01') rename to partition(dt = '2021-01-02');
    OK
    Time taken: 0.353 seconds
    hive> 
        > alter table test_part drop partition(dt='2020-12-31');
    Dropped the partition dt=2020-12-31
    OK
    Time taken: 0.151 seconds
    hive> alter table test_part drop partition(dt='2020-12-30') purge;
    Dropped the partition dt=2020-12-30
    OK
    Time taken: 0.135 seconds
    hive>

**我们来查看下分区的存储**  
可以看到一份分区一个文件夹，一个分区下可能有0个或多个文件

[root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_part
    Found 2 items
    drwxrwxrwt   - root hive          0 2020-12-29 16:03 /user/hive/warehouse/test.db/test_part/dt=2020-12-29
    drwxrwxrwt   - root hive          0 2020-12-29 16:09 /user/hive/warehouse/test.db/test_part/dt=2021-01-02

## 2.2 多分区测试 ##

代码:

-- 创建分区表
    create table test_part2(key int,value string) partitioned by (prod_name string,dt string);
    -- 查看分区表
    describe formatted test_part2;
    -- 往分区表录入数据
    insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-29') values (1,'abc');
    insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-30') values (2,'def');
    insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-31') values (3,'ghi');
    
    -- 新增分区
    alter table  test_part2 add partition(prod_name='PROD2',dt = '2020-12-29');
    -- 重命名分区
    alter table test_part2 partition(prod_name='PROD2',dt = '2020-12-29') rename to partition(prod_name='PROD3',dt = '2020-12-29');

测试记录:

hive> 
        > 
        > 
        > create table test_part2(key int,value string) partitioned by (prod_name string,dt string);
    OK
    Time taken: 0.09 seconds
    hive> describe formatted test_part2;
    OK
    # col_name              data_type               comment             
                     
    key                     int                                         
    value                   string                                      
                     
    # Partition Information          
    # col_name              data_type               comment             
                     
    prod_name               string                                      
    dt                      string                                      
                     
    # Detailed Table Information             
    Database:               test                     
    OwnerType:              USER                     
    Owner:                  root                     
    CreateTime:             Tue Dec 29 16:43:06 CST 2020     
    LastAccessTime:         UNKNOWN                  
    Retention:              0                        
    Location:               hdfs://nameservice1/user/hive/warehouse/test.db/test_part2       
    Table Type:             MANAGED_TABLE            
    Table Parameters:                
            COLUMN_STATS_ACCURATE   {\"BASIC_STATS\":\"true\"}
            numFiles                0                   
            numPartitions           0                   
            numRows                 0                   
            rawDataSize             0                   
            totalSize               0                   
            transient_lastDdlTime   1609231386          
                     
    # Storage Information            
    SerDe Library:          org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe       
    InputFormat:            org.apache.hadoop.mapred.TextInputFormat         
    OutputFormat:           org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat       
    Compressed:             No                       
    Num Buckets:            -1                       
    Bucket Columns:         []                       
    Sort Columns:           []                       
    Storage Desc Params:             
            serialization.format    1                   
    Time taken: 0.074 seconds, Fetched: 39 row(s)
    hive> insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-29') values (1,'abc');
    Query ID = root_20201229164322_9ffab4bf-8e7b-449f-ac07-91f73016da13
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:43:22 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0006, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0006/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0006
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:43:29,435 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:43:35,624 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 3.86 sec
    MapReduce Total cumulative CPU time: 3 seconds 860 msec
    Ended Job = job_1609141291605_0006
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-29/.hive-staging_hive_2020-12-29_16-43-22_143_1775810973752071302-1/-ext-10000
    Loading data to table test.test_part2 partition (prod_name=PROD1, dt=2020-12-29)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 3.86 sec   HDFS Read: 4319 HDFS Write: 107 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 3 seconds 860 msec
    OK
    Time taken: 16.222 seconds
    hive> insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-30') values (2,'def');
    Query ID = root_20201229164339_1a52188f-5fcb-4275-a26b-8a36db978218
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:43:40 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0007, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0007/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0007
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:43:47,977 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:43:55,193 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 3.61 sec
    MapReduce Total cumulative CPU time: 3 seconds 610 msec
    Ended Job = job_1609141291605_0007
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-30/.hive-staging_hive_2020-12-29_16-43-39_784_2410125837572976640-1/-ext-10000
    Loading data to table test.test_part2 partition (prod_name=PROD1, dt=2020-12-30)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 3.61 sec   HDFS Read: 4319 HDFS Write: 107 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 3 seconds 610 msec
    OK
    Time taken: 17.101 seconds
    hive> insert into test_part2 partition(prod_name='PROD1',dt = '2020-12-31') values (3,'ghi');
    Query ID = root_20201229164358_696aac78-0a49-46f0-bb8a-e408b22c48cb
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 16:43:58 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0008, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0008/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0008
    Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
    2020-12-29 16:44:06,382 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 16:44:12,570 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 3.46 sec
    MapReduce Total cumulative CPU time: 3 seconds 460 msec
    Ended Job = job_1609141291605_0008
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-31/.hive-staging_hive_2020-12-29_16-43-58_167_5034454344356683760-1/-ext-10000
    Loading data to table test.test_part2 partition (prod_name=PROD1, dt=2020-12-31)
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 1   Cumulative CPU: 3.46 sec   HDFS Read: 4319 HDFS Write: 107 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 3 seconds 460 msec
    OK
    Time taken: 17.146 seconds
    hive> alter table  test_part2 add partition(prod_name='PROD2',dt = '2020-12-29');
    OK
    Time taken: 0.114 seconds
    hive> alter table test_part2 partition(prod_name='PROD2',dt = '2020-12-29') rename to partition(prod_name='PROD3',dt = '2020-12-29');
    OK
    Time taken: 0.309 seconds
    hive>

**我们来查看下分区的存储**  
可以看到多级分区目录为多级，每一个prod\_name一个文件夹，产品文件夹下面，每一个dt是一个目录。  
多分区虽然会产生比较多的文件，如果数据量不大的情况下，谨慎使用。

[root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_part2
    Found 3 items
    drwxrwxrwt   - root hive          0 2020-12-29 16:43 /user/hive/warehouse/test.db/test_part2/prod_name=PROD1
    drwxrwxrwt   - root hive          0 2020-12-29 16:44 /user/hive/warehouse/test.db/test_part2/prod_name=PROD2
    drwxrwxrwt   - root hive          0 2020-12-29 16:44 /user/hive/warehouse/test.db/test_part2/prod_name=PROD3
    [root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_part2/prod_name=PROD1
    Found 3 items
    drwxrwxrwt   - root hive          0 2020-12-29 16:43 /user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-29
    drwxrwxrwt   - root hive          0 2020-12-29 16:43 /user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-30
    drwxrwxrwt   - root hive          0 2020-12-29 16:44 /user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-31
    [root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-29
    Found 1 items
    -rwxrwxrwt   3 root hive          6 2020-12-29 16:43 /user/hive/warehouse/test.db/test_part2/prod_name=PROD1/dt=2020-12-29/000000_0
    [root@hp1 ~]#

# 三.动态分区 #

官方文档对静态分区和动态分区的简单解释:

Static Partition (SP) columns: in DML/DDL involving multiple partitioning columns, the columns whose values are known at COMPILE TIME (given by user).
    Dynamic Partition (DP) columns: columns whose values are only known at EXECUTION TIME.

静态分区(SP)列:在涉及多个分区列的DML/DDL中，这些列的值在编译时已知(由用户给出)。  
Dynamic Partition (DP)列:在执行时才知道其值的列。

上面我们测试静态分区的时候，可以看到操作分区表的时候一定要指定分区，动态分区就解决了这个问题。

## 3.1 动态分区测试 ##

开启动态分区，需要调整如下配置:

set hive.exec.dynamic.partition=true;   --开启动态分区 默认为true，开启
    set hive.exec.dynamic.partition.mode=nonstrict; --指定动态分区模式，默认为strict，即必须指定至少一个分区为静态分区，nonstrict模式表示允许所有的分区字段都可以使用动态分区

**代码:**

CREATE TABLE emp_dynamic_partition (
     empno int,
     ename string,
     job string,
     mgr int,
     hiredate string,
     salary double,
     comm double
     )
     PARTITIONED BY (deptno int);
    
    insert into emp_dynamic_partition partition(deptno) select * from emp;

**测试记录:**

hive> 
        > 
        >  CREATE TABLE emp_dynamic_partition (
        >  empno int,
        >  ename string,
        >  job string,
        >  mgr int,
        >  hiredate string,
        >  salary double,
        >  comm double
        >  )
        >  PARTITIONED BY (deptno int);
    OK
    Time taken: 0.106 seconds
    hive> 
        > insert into emp_dynamic_partition select * from emp;
    FAILED: SemanticException 1:12 Need to specify partition columns because the destination table is partitioned. Error encountered near token 'emp_dynamic_partition'
    hive> 
        > set hive.exec.dynamic.partition.mode=nonstrict; 
    hive> 
        > 
        > insert into emp_dynamic_partition select * from emp;
    FAILED: SemanticException 1:12 Need to specify partition columns because the destination table is partitioned. Error encountered near token 'emp_dynamic_partition'
    hive> 
        > 
        > insert into emp_dynamic_partition partition(deptno) select * from emp;
    Query ID = root_20201229170212_e550dbfe-6d2e-49b0-83c8-9bc7d88c3144
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 17:02:13 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0009, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0009/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0009
    Hadoop job information for Stage-1: number of mappers: 2; number of reducers: 0
    2020-12-29 17:02:20,034 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 17:02:26,274 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 6.77 sec
    MapReduce Total cumulative CPU time: 6 seconds 770 msec
    Ended Job = job_1609141291605_0009
    Stage-4 is filtered out by condition resolver.
    Stage-3 is selected by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Launching Job 3 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 17:02:28 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0010, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0010/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0010
    Hadoop job information for Stage-3: number of mappers: 3; number of reducers: 0
    2020-12-29 17:02:39,398 Stage-3 map = 0%,  reduce = 0%
    2020-12-29 17:02:44,560 Stage-3 map = 67%,  reduce = 0%, Cumulative CPU 3.5 sec
    2020-12-29 17:02:48,675 Stage-3 map = 100%,  reduce = 0%, Cumulative CPU 5.11 sec
    MapReduce Total cumulative CPU time: 5 seconds 110 msec
    Ended Job = job_1609141291605_0010
    Loading data to table test.emp_dynamic_partition partition (deptno=null)
    
    
             Time taken to load dynamic partitions: 0.18 seconds
             Time taken for adding to write entity : 0.001 seconds
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 2   Cumulative CPU: 6.77 sec   HDFS Read: 13606 HDFS Write: 1041 HDFS EC Read: 0 SUCCESS
    Stage-Stage-3: Map: 3   Cumulative CPU: 5.11 sec   HDFS Read: 11072 HDFS Write: 635 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 11 seconds 880 msec
    OK
    Time taken: 37.464 seconds
    hive>

**可以看到根据deptno自动创建了3个分区**

[root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/emp_dynamic_partition
    Found 3 items
    drwxrwxrwt   - root hive          0 2020-12-29 17:02 /user/hive/warehouse/test.db/emp_dynamic_partition/deptno=10
    drwxrwxrwt   - root hive          0 2020-12-29 17:02 /user/hive/warehouse/test.db/emp_dynamic_partition/deptno=20
    drwxrwxrwt   -

## 3.2 动态分区和静态分区混合使用 ##

动态分区和静态分区可以混合使用

假设此时我有一个订单表，订单有一个状态。  
我需要做一个快照表，每天凌晨把所有订单的状态做一个快照，但是数据量比较大，除了按天分区外，我还想根据状态进行分区，此时我们可以将两种分区混合使用

**代码:**

create table test1(user_id int,prod_name string,apply_status string);
    insert into test1 values (1,'Prod1','申请中');
    insert into test1 values (2,'Prod1','审批中');
    insert into test1 values (3,'Prod1','完成');
    insert into test1 values (4,'Prod1','拒绝中');
    
    create table test_mix_partition
    (user_id    int,
     prod_name  string
    )
    partitioned by (dt string,apply_status string);
    
    insert into test_mix_partition partition(dt='2020-12-29',apply_status) select user_id,prod_name,apply_status from test1;

**测试记录**

hive> 
        > 
        > create table test_mix_partition
        > (user_id    int,
        >  prod_name  string
        > )
        > partitioned by (dt string,apply_status string);
    OK
    Time taken: 0.069 seconds
    hive> insert into test_mix_partition partition(dt='2020-12-29',apply_status) select user_id,prod_name,apply_status from test1;
    Query ID = root_20201229172136_c5b5e88f-f2ad-4863-944e-c1dc89be7030
    Total jobs = 3
    Launching Job 1 out of 3
    Number of reduce tasks is set to 0 since there's no reduce operator
    20/12/29 17:21:36 INFO client.ConfiguredRMFailoverProxyProvider: Failing over to rm69
    Starting Job = job_1609141291605_0015, Tracking URL = http://hp3:8088/proxy/application_1609141291605_0015/
    Kill Command = /opt/cloudera/parcels/CDH-6.3.1-1.cdh6.3.1.p0.1470567/lib/hadoop/bin/hadoop job  -kill job_1609141291605_0015
    Hadoop job information for Stage-1: number of mappers: 2; number of reducers: 0
    2020-12-29 17:21:43,261 Stage-1 map = 0%,  reduce = 0%
    2020-12-29 17:21:49,445 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 3.77 sec
    MapReduce Total cumulative CPU time: 3 seconds 770 msec
    Ended Job = job_1609141291605_0015
    Stage-4 is selected by condition resolver.
    Stage-3 is filtered out by condition resolver.
    Stage-5 is filtered out by condition resolver.
    Moving data to directory hdfs://nameservice1/user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29/.hive-staging_hive_2020-12-29_17-21-36_213_8707202021987000828-1/-ext-10000
    Loading data to table test.test_mix_partition partition (dt=2020-12-29, apply_status=null)
    
    
             Time taken to load dynamic partitions: 0.175 seconds
             Time taken for adding to write entity : 0.001 seconds
    MapReduce Jobs Launched: 
    Stage-Stage-1: Map: 2   Cumulative CPU: 3.77 sec   HDFS Read: 9390 HDFS Write: 423 HDFS EC Read: 0 SUCCESS
    Total MapReduce CPU Time Spent: 3 seconds 770 msec
    OK
    Time taken: 14.95 seconds
    hive> 
    
    
    [root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_mix_partition
    Found 1 items
    drwxrwxrwt   - root hive          0 2020-12-29 17:21 /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29
    [root@hp1 ~]# 
    [root@hp1 ~]# hadoop fs -ls /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29
    Found 4 items
    drwxrwxrwt   - root hive          0 2020-12-29 17:21 /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29/apply_status=完成
    drwxrwxrwt   - root hive          0 2020-12-29 17:21 /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29/apply_status=审批中
    drwxrwxrwt   - root hive          0 2020-12-29 17:21 /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29/apply_status=拒绝中
    drwxrwxrwt   - root hive          0 2020-12-29 17:21 /user/hive/warehouse/test.db/test_mix_partition/dt=2020-12-29/apply_status=申请中
    [root@hp1 ~]#

# 四.分区的其它操作 #

## 4.1 恢复分区 ##

语法:

MSCK [REPAIR] TABLE table_name [ADD/DROP/SYNC PARTITIONS];

msck repair table命令执行后Hive会检测如果HDFS目录下存在 但表的metastore中不存在的partition元信息，更新到metastore中。如果有一张表已经存放好几年了，用这个命令去执行的话 半天都反应不了，所以这个命令太暴力了，生产中不推荐使用。可以用Add partition来添加分区。

## 4.2 归档分区 ##

语法:

ALTER TABLE table_name ARCHIVE PARTITION partition_spec;
    ALTER TABLE table_name UNARCHIVE PARTITION partition_spec;

归档分区可以减轻 name node的压力，当然，数据量非常大、文件非常多(千万级别)的时候，再考虑做归档。

## 4.3 交换分区 ##

EXCHANGE PARTITION命令将一个分区从源表移动到目标表，并更改每个表的元数据。

**约束:**

1.  目标表不能包含要交换的分区。
2.  如果有索引，操作将失败。
3.  交换分区不允许将事务表作为源或目标。或者，使用LOAD DATA或INSERT OVERWRITE命令在事务性表之间移动分区。
4.  此命令要求源表名和目标表名具有相同的表模式。
5.  如果模式不同，抛出以下异常:  
    The tables have different schemas. Their partitions cannot be exchanged

**语法:**

ALTER TABLE <dest_table> EXCHANGE PARTITION (<[partial] partition spec>) WITH TABLE <src_table>

**例1:**

-- 创建两个分区表
    CREATE TABLE T1(a string, b string) PARTITIONED BY (ds string);
    CREATE TABLE T2(a string, b string) PARTITIONED BY (ds string);
    ALTER TABLE T1 ADD PARTITION (ds='1');
     
    -- 将t1表的分区 ds=‘1' 移动到t2表
    ALTER TABLE T2 EXCHANGE PARTITION (ds='1') WITH TABLE T1;

测试记录:

hive> 
        > CREATE TABLE T1(a string, b string) PARTITIONED BY (ds string);
    OK
    Time taken: 0.081 seconds
    hive> CREATE TABLE T2(a string, b string) PARTITIONED BY (ds string);
    OK
    Time taken: 0.085 seconds
    hive> ALTER TABLE T1 ADD PARTITION (ds='1');
    OK
    Time taken: 0.103 seconds
    hive> ALTER TABLE T2 EXCHANGE PARTITION (ds='1') WITH TABLE T1;
    OK
    Time taken: 0.303 seconds
    hive>

**例2**

-- 创建2个多分区列的分区表
    CREATE TABLE T1 (a string, b string) PARTITIONED BY (ds string, hr string);
    CREATE TABLE T2 (a string, b string) PARTITIONED BY (ds string, hr string);
    ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '00');
    ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '01');
    ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '03');
     
    --  ds='1' 的三个分区同时移动到 t1分区表
    ALTER TABLE T2 EXCHANGE PARTITION (ds='1') WITH TABLE T1;

测试记录:

hive> 
        > 
        > CREATE TABLE T1 (a string, b string) PARTITIONED BY (ds string, hr string);
    OK
    Time taken: 0.092 seconds
    hive> CREATE TABLE T2 (a string, b string) PARTITIONED BY (ds string, hr string);
    OK
    Time taken: 0.073 seconds
    hive> ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '00');
    OK
    Time taken: 0.106 seconds
    hive> ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '01');
    OK
    Time taken: 0.122 seconds
    hive> ALTER TABLE T1 ADD PARTITION (ds = '1', hr = '03');
    OK
    Time taken: 0.093 seconds
    hive> ALTER TABLE T2 EXCHANGE PARTITION (ds='1') WITH TABLE T1;
    OK
    Time taken: 0.337 seconds
    hive>

# 参考 #

1.https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL\#LanguageManualDDL-PartitionedTables