Data science Software Course Training in Ameerpet Hyderabad

Data science Software Course Training in Ameerpet Hyderabad

Monday, 6 June 2016

sqoop import and export lesson 3


Sqoop import into Hive Tables
_________________________________
hive> create table atab(id int , name string,
    >   sal int, sex string, dno int);
OK
Time taken: 2.004 seconds
hive>
default database in hive is "default"
hdfs location of default database
   /user/hive/warehouse
when hive table is created, a directory will be created in  warehouse location.
  ex: table  atab
   hdfs   /user/hive/warehouse/atab

hive> create table atab(id int , name string,
    >   sal int, sex string, dno int);
OK
Time taken: 2.004 seconds
[training@localhost ~]$ sqoop import  --connect jdbc:mysql://localhost/practice  --username root  --table samp -m 1  --hive-import --hive-table atab --append





hive> select * from atab;
OK
101     aaaa    10000   m       12
102     addaaa  20000   f       12
103     ada     20000   f       13
104     ada     50000   f       11
105     addda   70000   m       12
106     adddda  80000   m       11
107     xadddda 70000   f       12
Time taken: 0.217 seconds
hive>
____
hive> create database testx;
OK
Time taken: 0.029 seconds
hive> use testx
    > ;
OK
Time taken: 0.02 seconds
hive> create table dummy(a int);
OK
Time taken: 0.045 seconds
hive>

_____________
[training@localhost ~]$ hadoop fs -ls /user/hive/warehouse/atab
Found 1 items
-rw-r--r--   1 training supergroup        146 2016-06-05 19:22 /user/hive/warehouse/atab/part-m-00000
[training@localhost ~]$ hadoop fs -cat /user/hive/warehouse/atab/part-m-00000
101 aaaa 10000 m 12
102 addaaa 20000 f 12
103 ada 20000 f 13
104 ada 50000 f 11
105 addda 70000 m 12
106 adddda 80000 m 11
107 xadddda 70000 f 12
[training@localhost ~]$
sqoop write two types of delimiters,
 i) while writing into hdfs,
   sq writes "," delimiter.
 ii) while writing into hive tables,
  sq writes '\001'  delimiter
    ctrl+A
 ____________________________
default delimiter for hive table \001
if hive table  has different delimiter...
 how to import?

___________
hive> create table ctab(id int, name string,
    >   sal int , sex string, dno int)    
    > row format delimited
    >    fields terminated by ',';
OK
Time taken: 0.044 seconds
[training@localhost ~]$ sqoop import  --connect jdbc:mysql://localhost/practice  --username root  --table samp -m 1  --hive-import --hive-table ctab --append



hive> select * from ctab;
OK
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    NULL    NULL
Time taken: 0.074 seconds
hive>
sqoop has written \001 as delimiter, but table has ',' delimiter.
   in the backend file (part-m-00000) there are 0 commas. so entire line is treated as single field. but this is string, in table first col is id which int, thats why id became null.
 there is only one field in files, thats why remaing columns name,sal,sex,dno became null.
solution.  Delimiter should be changed at the time of importing.
_______________
hive> create table dtab like ctab;
[training@localhost ~]$ sqoop import  --connect jdbc:mysql://localhost/practice  --username root  --table samp -m 1  --hive-import --hive-table dtab --append --fields-terminated-by ','
hive> select * from dtab;
OK
101     aaaa    10000   m       12
102     addaaa  20000   f       12
103     ada     20000   f       13
104     ada     50000   f       11
105     addda   70000   m       12
106     adddda  80000   m       11
107     xadddda 70000   f       12
Time taken: 0.073 seconds
hive>
_______________________________
[training@localhost ~]$ cat  >   samp1
100,200,300
300,600,800
100,3000,456
100,456,222
[training@localhost ~]$ hadoop fs -mkdir  exp
[training@localhost ~]$ hadoop fs -copyFromLocal samp1 exp

mysql> create table mysamp(a int, b int, c int);
Query OK, 0 rows affected (0.00 sec)
mysql> select * from mysamp;
Empty set (0.00 sec)

[training@localhost ~]$ sqoop export   --connect  jdbc:mysql://localhost/practice  --username root  --table mysamp  --export-dir  exp/samp1

mysql> select * from mysamp;
+------+------+------+
| a    | b    | c    |
+------+------+------+
|  100 |  200 |  300 |
|  300 |  600 |  800 |
|  100 | 3000 |  456 |
|  100 |  456 |  222 |
+------+------+------+
4 rows in set (0.00 sec)
mysql>
[training@localhost ~]$ cat > samp2
10      20      30
12      34      90
12      45      67
[training@localhost ~]$ hadoop fs -copyFromLocal samp2 exp
[training@localhost ~]$
[training@localhost ~]$ sqoop export   --connect  jdbc:mysql://localhost/practice  --username root  --table mysamp  --export-dir  exp/samp2 --input-fields-terminated-by '\t'
exporting hive results into rdbms.
hive> create table results1(dno int,
   sex  string, tot int);

hive> insert overwrite table results1                  
    >   select dno, sex, sum(sal) from dtab
    >     group by dno, sex;
hive> select * from results1;
OK
11      f       50000
11      m       80000
12      f       90000
12      m       80000
13      f       20000
Time taken: 0.088 seconds
hive>
mysql> create table Aggr(dno int , sex char(1),
    ->    tot int);
Query OK, 0 rows affected (0.00 sec)
mysql>
[training@localhost ~]$ sqoop export   --connect  jdbc:mysql://localhost/practice  --username root  --table Aggr     --export-dir  /user/hive/warehouse/results1/000000_0        --input-fields-terminated-by '\001'
mysql> select * from Aggr;
+------+------+-------+
| dno  | sex  | tot   |
+------+------+-------+
|   11 | f    | 50000 |
|   11 | m    | 80000 |
|   12 | f    | 90000 |
|   12 | m    | 80000 |
|   13 | f    | 20000 |
+------+------+-------+
5 rows in set (0.00 sec)
mysql>
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3 comments:

  1. Sir,
    Please upload the text files for 8th June and 9th June also.

    ThankYou.

    ReplyDelete
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