压缩率和压缩速度成反比：
压缩比：bzip2 > gzip > lzo > snappy ，压缩速度：snappy > lzo> gzip > bzip2
压缩以及解压是高消耗cpu的过程，故若机器的负载很高时就不能使用压缩，资源不够可通过扩容快速解决
Hive中建表（列式+压缩）语句：
（1）orc格式
#Hive中默认压缩是zlib，写不写都一样
create table page_views_orc_zlib
ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
STORED AS ORC
TBLPROPERTIES("orc.compress"="ZLIB")
as select * from page_views;
create table page_views_orc_snappy
ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
STORED AS ORC
TBLPROPERTIES("orc.compress"="SNAPPY")
as select * from page_views;
（2）parquent格式
create table page_views_parquet
ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
STORED AS PARQUET
as select * from page_views;
set parquet.compression=gzip;
create table page_views_parquet_gzip
ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
STORED AS PARQUET
as select * from page_views;