Hive學習之基礎語法
1、建立資料庫
create database 資料庫名;
2、使用資料庫
use 資料庫名;
3、建立表
內部表:表目錄安裝hive的規範來部署,位於hive倉庫目錄/user/hive/warehouse中
create table t_pv_log(ip string,url string,access_time string )
row format delimited
fields terminated by ',';
外部表:表目錄由使用者指定
在hdfs上建立資料夾
hadoop fs -mkdir -p /pvlog/2017-09-16
準備測試資料
192.168.33.1,http://sina.com/a,2017-09-16 12:52:01
192.168.33.2,http://sina.com/a,2017-09-16 12:51:01
192.168.33.1,http://sina.com/a,2017-09-16 12:50:01
192.168.33.2,http://sina.com/b,2017-09-16 12:49:01
192.168.33.1,http://sina.com/b,2017-09-16 12:48:01
192.168.33.4,http://sina.com/a,2017-09-16 12:47:01
192.168.33.3,http://sina.com/a,2017-09-16 12:46:01
192.168.33.2,http://sina.com/b,2017-09-16 12:45:01
192.168.33.2,http://sina.com/a,2017-09-16 12:44:01
192.168.33.1,http://sina.com/a,2017-09-16 13:43:01
將資料上傳至hdfs中/pvlog/2017-09-16
hadoop fs -put ./pv.log /pvlog/2017-09-16
建立外部表:
create external table t_pv_log(ip string,url string,access_time string )
row format delimited
fields terminated by ','
location '/pvlog/2017-09-16';
內部表和外部表區別:
內部表刪除時表和資料同時刪除
外部表只刪除表,資料檔案依舊存在於hdfs系統中
4、分割槽表
分割槽表的實質是:在表目錄中為資料檔案建立分割槽子目錄,以便於在查詢時,MR程式可以針對分割槽子目錄中的資料進行處理,縮減讀取資料的範圍。
比如,網站每天產生的瀏覽記錄,瀏覽記錄應該建一個表來存放,但是,有時,我們可能只需要對每一天的瀏覽記錄進行分析
這時,就可以將這個表建為分割槽表,每天的資料匯入其中的一個分割槽
準備資料:
192.168.33.1,http://sina.com/a,2017-09-16 12:52:01
192.168.33.2,http://sina.com/a,2017-09-16 12:51:01
192.168.33.1,http://sina.com/a,2017-09-16 12:50:01
192.168.33.2,http://sina.com/b,2017-09-16 12:49:01
192.168.33.1,http://sina.com/b,2017-09-15 12:48:01
192.168.33.4,http://sina.com/a,2017-09-15 12:47:01
192.168.33.3,http://sina.com/a,2017-09-15 12:46:01
192.168.33.2,http://sina.com/b,2017-09-15 12:45:01
192.168.33.2,http://sina.com/a,2017-09-15 12:44:01
192.168.33.1,http://sina.com/a,2017-09-15 13:43:01
建立分割槽表
create table t_pv_log(ip string,url string ,access_time string)
partitioned by(day string)
row format delimited
fields terminated by ',';
將資料載入入新建的表中:
load data local inpath '/usr/local/hivetest/pv.log.15' into table t_pv_log partition(day='20170916');
通過分割槽欄位查詢資料:
0: jdbc:hive2://hadoop00:10000> select * from t_pv_log where day ='20170916';
+---------------+--------------------+-----------------------+---------------+--+
| t_pv_log.ip | t_pv_log.url | t_pv_log.access_time | t_pv_log.day |
+---------------+--------------------+-----------------------+---------------+--+
| 192.168.33.1 | http://sina.com/a | 2017-09-16 12:52:01 | 20170916 |
| 192.168.33.2 | http://sina.com/a | 2017-09-16 12:51:01 | 20170916 |
| 192.168.33.1 | http://sina.com/a | 2017-09-16 12:50:01 | 20170916 |
| 192.168.33.2 | http://sina.com/b | 2017-09-16 12:49:01 | 20170916 |
| 192.168.33.1 | http://sina.com/b | 2017-09-16 12:48:01 | 20170916 |
| 192.168.33.4 | http://sina.com/a | 2017-09-16 12:47:01 | 20170916 |
| 192.168.33.3 | http://sina.com/a | 2017-09-16 12:46:01 | 20170916 |
| 192.168.33.2 | http://sina.com/b | 2017-09-16 12:45:01 | 20170916 |
| 192.168.33.2 | http://sina.com/a | 2017-09-16 12:44:01 | 20170916 |
| 192.168.33.1 | http://sina.com/a | 2017-09-16 13:43:01 | 20170916 |
+---------------+--------------------+-----------------------+---------------+--+
5、檔案匯入
方式1:
手動用hdfs命令,將檔案放入表目錄。
方式2:在hive的互動式shell中用hive命令來匯入本地資料到表目錄
load data local inpath '/usr/local/data/' into table order;
方式3:用hive命令匯入hdfs中的資料檔案到表目錄
load data inpath ‘access.log’ into table t_access partition(day='20170916');
注意匯入本地檔案和導HDFS檔案區別:
本地檔案匯入表:複製
HDFS檔案匯入表:移動