测试存储和压缩
官网：https://cwiki.apache.org/confluence/display/Hive/LanguageManual+ORC
ORC存储方式的压缩：
| Key |
Default |
Notes |
| orc.compress |
ZLIB |
high level compression (one of NONE, ZLIB, SNAPPY) |
| orc.compress.size |
262,144 |
number of bytes in each compression chunk |
| orc.stripe.size |
268,435,456 |
number of bytes in each stripe |
| orc.row.index.stride |
10,000 |
number of rows between index entries (must be >= 1000) |
| orc.create.index |
true |
whether to create row indexes |
| orc.bloom.filter.columns |
"" |
comma separated list of column names for which bloom filter should be created |
| orc.bloom.filter.fpp |
0.05 |
false positive probability for bloom filter (must >0.0 and <1.0) |
注意：所有关于ORCFile的参数都是在HQL语句的TBLPROPERTIES字段里面出现
1）创建一个非压缩的的ORC存储方式
（1）建表语句
create table log_orc_zlib(
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"="ZLIB");
（2）插入数据
insert into log_orc_zlib select * from log_text;
（3）查看插入后数据
hive (default)> dfs -du -h /user/hive/warehouse/log_orc_none/ ;
7.7 M /user/hive/warehouse/log_orc_none/000000_0
2）创建一个SNAPPY压缩的ORC存储方式
（1）建表语句
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）插入数据
insert into log_orc_snappy select * from log_text;
（3）查看插入后数据
hive (default)> dfs -du -h /user/hive/warehouse/log_orc_snappy/ ;
3.8 M /user/hive/warehouse/log_orc_snappy/000000_0
3）上一节中默认创建的ORC存储方式，导入数据后的大小为
2.8 M /user/hive/warehouse/log_orc/000000_0
比Snappy压缩的还小。原因是orc存储文件默认采用ZLIB压缩，ZLIB采用的是deflate压缩算法。比snappy压缩的小。
4）存储方式和压缩总结
在实际的项目开发当中，hive表的数据存储格式一般选择：orc或parquet。压缩方式一般选择snappy，lzo。