本篇文章主要介紹使用Sqoop1將MySQL 導入數據到 HDFS。
說明:
1、Sqoop 與數據庫進行通信,獲取數據庫表的元數據信息
2、Sqoop啓動一個Map-Only的MapReduce作業,利用元數據信息並行將數據寫入Hadoop
簡要步驟:
①、mysql中創建數據庫sqoop
②、創建表dept和emp表
③、插入數據
④、從mysql導出數據到HDFS
⑤、查看數據
⑥、導入過程遇到的錯誤以及解決方案
詳細步驟:
一、mysql中創建數據庫sqoop
create database sqoop;
use sqoop;
二、創建表dept和emp表
CREATE TABLE DEPT(
DEPTNO int(2) PRIMARY KEY,
DNAME VARCHAR(14),
LOC VARCHAR(13)
);
CREATE TABLE EMP(
EMPNO int(4) PRIMARY KEY,
ENAME VARCHAR(10),
JOB VARCHAR(9),
MGR int(4),
HIREDATE DATE,
SAL int(7),
COMM int(7),
DEPTNO int(2),
foreign key(deptno) references DEPT(DEPTNO)
);
三、插入數據
use sqoop;
INSERT INTO DEPT VALUES
(10,'ACCOUNTING','NEW YORK');
INSERT INTO DEPT VALUES (20,'RESEARCH','DALLAS');
INSERT INTO DEPT VALUES
(30,'SALES','CHICAGO');
INSERT INTO DEPT VALUES
(40,'OPERATIONS','BOSTON');
INSERT INTO EMP VALUES
(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20);
INSERT INTO EMP VALUES
(7499,'ALLEN','SALESMAN',7698,'1981-2-20',1600,300,30);
INSERT INTO EMP VALUES
(7521,'WARD','SALESMAN',7698,'1981-2-22',1250,500,30);
INSERT INTO EMP VALUES
(7566,'JONES','MANAGER',7839,'1981-4-2',2975,NULL,20);
INSERT INTO EMP VALUES
(7654,'MARTIN','SALESMAN',7698,'1981-9-28',1250,1400,30);
INSERT INTO EMP VALUES
(7698,'BLAKE','MANAGER',7839,'1981-5-1',2850,NULL,30);
INSERT INTO EMP VALUES
(7782,'CLARK','MANAGER',7839,'1981-6-9',2450,NULL,10);
INSERT INTO EMP VALUES
(7788,'SCOTT','ANALYST',7566,'87-7-13',3000,NULL,20);
INSERT INTO EMP VALUES
(7839,'KING','PRESIDENT',NULL,'1981-11-17',5000,NULL,10);
INSERT INTO EMP VALUES
(7844,'TURNER','SALESMAN',7698,'1981-9-8',1500,0,30);
INSERT INTO EMP VALUES
(7876,'ADAMS','CLERK',7788,'87-7-13',1100,NULL,20);
INSERT INTO EMP VALUES
(7900,'JAMES','CLERK',7698,'1981-12-3',950,NULL,30);
INSERT INTO EMP VALUES
(7902,'FORD','ANALYST',7566,'1981-12-3',3000,NULL,20);
INSERT INTO EMP VALUES
(7934,'MILLER','CLERK',7782,'1982-1-23',1300,NULL,10);
四、從mysql導出數據到HDFS
①導入數據使用import命令,輸入如下命令查看幫助說明
sqoop help import
②輸入命令導入數據
其中-m 1 參數代表的含義是使用多少個並行,這個參數的值是1,說明沒有開啓並行功能。
將m參數的數值調爲5或者更大,Sqoop就會開啓5個進程,同時進行數據的導入操作。
注意:mysql數據庫的表中需要有個主鍵,如果沒有主鍵的話需要手動選取一個合適的拆分字段。
-m 1是map的數量
sqoop import --connect jdbc:mysql://localhost:3306/sqoop --username root --password P@assWord123 --table EMP -m 1
錯誤解決方案:
Sqoop 導入數據報錯:No columns to generate for ClassWriter
啓動mr歷史記錄命令:
mr-jobhistory-daemon.sh start historyserver
五、查看數據
六、錯誤以及解決方案
1、Sqoop: java.lang.RuntimeException: Could not load db driver class: com.mysql.jdbc.Driver
2、https://blog.csdn.net/zjh_746140129/article/details/84962235