近日學習hive過程中，其基本操作與mysql類似，不做贅述；特別的，針對一些hive中的建表命令進行了整理。
//建立表,external 外部表
$hive>create external table if not exists t2(id int,name string,age int) comment 'xx' row format delimited fields terminated by ',' stored as textfile ;
//檢視表資料
$hive>desc t2 ;
$hive>desc formatted t2 ;
//載入資料到hive表
$hive>load data local inpath '/home/***/customers.txt' into table t2 ; //local上傳檔案
$hive>load data inpath '/user/***/customers.txt' [overwrite] into table t2 ; //移動檔案
//複製表
mysql>create table tt as select * from users ; //攜帶資料和表結構
mysql>create table tt like users ; //不帶資料，只有表結構
hive>create table tt as select * from users ;
hive>create table tt like users ;
//count()查詢要轉成mr
$hive>select count(*) from t2 ;
$hive>select id,name from t2 ;
//$hive>select * from t2 order by id desc ; //mr
//啟用/禁用表
$hive>alter table t2 enable no_drop; //不允許刪除
$hive>alter table t2 disable no_drop; //允許刪除
//分割槽表,優化手段之一，從目錄的層面控制搜尋資料的範圍。
//建立分割槽表.
$hive>create table t3(id int,name string,age int) partitioned by (year int, month int) row format delimited fields terminated by ',' ;
//顯式表的分割槽資訊
$hive>show partitions t3;
//新增分割槽,建立目錄
$hive>alter table t3 add partition (year=2014, month=12);
//刪除分割槽
hive>alter table employee_partitioned drop if exists partition (year=2014, month=11);
//分割槽結構
hive>/user/hive/warehouse/mydb2.db/t3/year=2014/month=11
hive>/user/hive/warehouse/mydb2.db/t3/year=2014/month=12
//載入資料到分割槽表
hive>load data local inpath '/home/centos/customers.txt' into table t3 partition(year=2014,month=11);
//建立桶表
$hive>create table t4(id int,name string,age int) clustered by (id) into 3 buckets row format delimited fields terminated by ',' ;
//載入資料不會進行分桶操作
$hive>load data local inpath '/home/centos/customers.txt' into table t4 ;
//查詢t3表資料插入到t4中。
$hive>insert into t4 select id,name,age from t3 ;
//桶表的數量如何設定?
//評估資料量，保證每個桶的資料量block的2倍大小。
//連線查詢
$hive>create table customers(id int,name string,age int) row format delimited fields terminated by ',' ;
$hive>create table orders(id int,orderno string,price float,cid int) row format delimited fields terminated by ',' ;
//載入資料到表
//內連線查詢
hive>select a.*,b.* from customers a , orders b where a.id = b.cid ;
//左外
hive>select a.*,b.* from customers a left outer join orders b on a.id = b.cid ;
hive>select a.*,b.* from customers a right outer join orders b on a.id = b.cid ;
hive>select a.*,b.* from customers a full outer join orders b on a.id = b.cid ;
//explode,炸裂,表生成函式。
//使用hive實現單詞統計
//1.建表
$hive>create table doc(line string) row format delimited fields terminated by ',' ;
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