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hive基础知识五

运维开发网 https://www.qedev.com 2020-05-18 16:04 出处:网络
Hive 主流文件存储格式对比 1、存储文件的压缩比测试 1.1 测试数据 https://github.com/liufengji/Compression_Format_Data ? log.txt 大小为18.1 M 1.2 TextFile 创建表,存储数据格式为TextFile create table log_text ( track_time string, url strin

Hive 主流文件存储格式对比

1、存储文件的压缩比测试

1.1 测试数据
https://github.com/liufengji/Compression_Format_Data
?
log.txt 大小为18.1 M
1.2 TextFile
  • 创建表,存储数据格式为TextFile

create table log_text (
track_time string,
url string,
session_id string,
referer string,
ip string,
end_user_id string,
city_id string
)
row format delimited fields terminated by ‘\t‘
stored as textfile ;
  • 向表中加载数据

load data local inpath ‘/home/hadoop/log.txt‘ into table log_text ;
  • 查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_text;
?
+------------------------------------------------+--+
|                   DFS Output                   |
+------------------------------------------------+--+
| 18.1 M  /user/hive/warehouse/log_text/log.txt  |
+------------------------------------------------+--+
1.3 Parquet
  • 创建表,存储数据格式为 parquet

create table log_parquet  (
track_time string,
url string,
session_id string,
referer string,
ip string,
end_user_id string,
city_id string
)
row format delimited fields terminated by ‘\t‘
stored as parquet;
  • 向表中加载数据

insert into table log_parquet select * from log_text;
  • 查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_parquet;
?
+----------------------------------------------------+--+
|                     DFS Output                     |
+----------------------------------------------------+--+
| 13.1 M  /user/hive/warehouse/log_parquet/000000_0  |
+----------------------------------------------------+--+
1.4 ORC
  • 创建表,存储数据格式为ORC

create table log_orc  (
track_time string,
url string,
session_id string,
referer string,
ip string,
end_user_id string,
city_id string
)
row format delimited fields terminated by ‘\t‘
stored as orc  ;
  • 向表中加载数据

insert into table log_orc select * from log_text ;
  • 查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_orc;
+-----------------------------------------------+--+
|                  DFS Output                   |
+-----------------------------------------------+--+
| 2.8 M  /user/hive/warehouse/log_orc/000000_0  |
+-----------------------------------------------+--+
1.5 存储文件的压缩比总结
ORC >  Parquet >  textFile

2、存储文件的查询速度测试

2.1 TextFile
select count(*) from log_text;
+---------+--+
|   _c0   |
+---------+--+
| 100000  |
+---------+--+
1 row selected (16.99 seconds)
2.2 Parquet
select count(*) from log_parquet;
+---------+--+
|   _c0   |
+---------+--+
| 100000  |
+---------+--+
1 row selected (17.994 seconds)
2.3 ORC
select count(*) from log_orc;
+---------+--+
|   _c0   |
+---------+--+
| 100000  |
+---------+--+
1 row selected (15.943 seconds)
2.4 存储文件的查询速度总结
ORC > TextFile > Parquet

3、存储和压缩结合

  • 使用压缩的优势是可以最小化所需要的磁盘存储空间,以及减少磁盘和网络io操作

  • 官网地址

    • https://cwiki.apache.org/confluence/display/Hive/LanguageManual+ORC

  • ORC支持三种压缩:ZLIB,SNAPPY,NONE。最后一种就是不压缩,orc默认采用的是ZLIB压缩

3.1 创建一个非压缩的的ORC存储方式表
  • 1、创建一个非压缩的的ORC表

create table log_orc_none (
track_time string,
url string,
session_id string,
referer string,
ip string,
end_user_id string,
city_id string
)
row format delimited fields terminated by ‘\t‘
stored as orc tblproperties("orc.compress"="NONE") ;
  • 2、加载数据

insert into table log_orc_none select * from log_text ;
  • 3、查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_orc_none;
+----------------------------------------------------+--+
|                     DFS Output                     |
+----------------------------------------------------+--+
| 7.7 M  /user/hive/warehouse/log_orc_none/000000_0  |
+----------------------------------------------------+--+
3.2 创建一个snappy压缩的ORC存储方式表
  • 1、创建一个snappy压缩的的ORC表

create table log_orc_snappy (
track_time string,
url string,
session_id string,
referer string,
ip string,
end_user_id string,
city_id string
)
row format delimited fields terminated by ‘\t‘
stored as orc tblproperties("orc.compress"="SNAPPY") ;
  • 2、加载数据

insert into table log_orc_snappy select * from log_text ;
  • 3、查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_orc_snappy;
+------------------------------------------------------+--+
|                      DFS Output                      |
+------------------------------------------------------+--+
| 3.8 M  /user/hive/warehouse/log_orc_snappy/000000_0  |
+------------------------------------------------------+--+
3.3 创建一个ZLIB压缩的ORC存储方式表
  • 不指定压缩格式的就是默认的采用ZLIB压缩

    • 可以参考上面创建的 log_orc 表

  • 查看表的数据量大小

dfs -du -h /user/hive/warehouse/log_orc;
+-----------------------------------------------+--+
|                  DFS Output                   |
+-----------------------------------------------+--+
| 2.8 M  /user/hive/warehouse/log_orc/000000_0  |
+-----------------------------------------------+--+
3.4 存储方式和压缩总结
  • orc 默认的压缩方式ZLIB比Snappy压缩的还小。

  • 在实际的项目开发当中,hive表的数据存储方式一般选择:orc或parquet

  • 由于snappy的压缩和解压缩 效率都比较高,压缩方式一般选择snappy

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