hive经常使用命令

启动hive：
start-all.sh
hive

进入hive以后，建立一个hive数据库库：
create database if not exists db;

建立一个新表，结构与其余同样
hive> create table new_table like records;

建立分区表：
hive> create table logs(ts bigint,line string) partitioned by (dt String,country String);

加载分区表数据：
hive> load data local inpath '/home/hive/partitions/files' into table logs partition (dt='2017-08-01',country='GB');

展现表中有多少分区：
hive> show partitions logs;

展现全部表：
hive> show tables;
lists all the tables
hive> show tables '.*s';

显示表的结构信息
hive> DESCRIBE invites;
shows the list of columns

更新表的名称：
hive> ALTER TABLE source RENAME TO target;

添加新一列
hive> ALTER TABLE invites ADD COLUMNS (new_col2 INT COMMENT 'a comment');

删除表：
hive> DROP TABLE records;
删除表中数据，但要保持表的结构定义
hive> dfs -rmr /user/hive/warehouse/records;

从本地文件加载数据：
hive> LOAD DATA LOCAL INPATH '/home/hadoop/input/ncdc/micro-tab/sample.txt' OVERWRITE INTO TABLE records;

显示全部函数：
hive> show functions;

查看函数用法：
hive> describe function substr;

查看数组、map、结构
hive> select col1[0],col2['b'],col3.c from complex;

内链接：
hive> SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

查看hive为某个查询使用多少个MapReduce做业
hive> Explain SELECT sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

外链接：
hive> SELECT sales.*, things.* FROM sales LEFT OUTER JOIN things ON (sales.id = things.id);
hive> SELECT sales.*, things.* FROM sales RIGHT OUTER JOIN things ON (sales.id = things.id);
hive> SELECT sales.*, things.* FROM sales FULL OUTER JOIN things ON (sales.id = things.id);

in查询：Hive不支持，但能够使用LEFT SEMI JOIN
hive> SELECT * FROM things LEFT SEMI JOIN sales ON (sales.id = things.id);

Map链接：Hive能够把较小的表放入每一个Mapper的内存来执行链接操做
hive> SELECT /*+ MAPJOIN(things) */ sales.*, things.* FROM sales JOIN things ON (sales.id = things.id);

INSERT OVERWRITE TABLE ..SELECT：新表预先存在
hive> FROM records2
> INSERT OVERWRITE TABLE stations_by_year SELECT year, COUNT(DISTINCT station) GROUP BY year
> INSERT OVERWRITE TABLE records_by_year SELECT year, COUNT(1) GROUP BY year
> INSERT OVERWRITE TABLE good_records_by_year SELECT year, COUNT(1) WHERE temperature != 9999 AND (quality = 0 OR quality = 1 OR quality = 4 OR quality = 5 OR quality = 9) GROUP BY year;

CREATE TABLE ... AS SELECT：新表表预先不存在hive>CREATE TABLE target AS SELECT col1,col2 FROM source;