Composite types of Hive

hive Array, map, struct use

Hive provides a composite data type:
Structs:structs internal data can be accessed via dot (.), for example, a column C in a table is of type struct{a int; b int}, we can access domain A by C.A
Maps (k-v pair): Access to the specified domain can be done through ["Specified domain name"], for example, a map m contains a group-"gid of the kv pair, the GID value can be obtained by m[' group ')
The data in Arrays:array is the same type, for example, if the element in array a [' A ', ' B ', ' C '], then the value of a[1] is ' B '

Struct Use

Build table:

· Hive>create table student_test (id INT, infostruct<name:string, age:int>)

· > ROW FORMAT delimited fields Terminatedby ', '

· > COLLECTION ITEMS TERMINATED by ': ';

· Ok

· timetaken:0.446 seconds

' Field TERMINATED by ': Separator between fields and fields
' COLLECTION ITEMS TERMINATED by ': delimiter for each item in a field
Import data:

· $ cattest5.txt

· 1,zhou:30

· 2,yan:30

· 3,chen:20

· 4,li:80

· Hive>load DATA LOCAL inpath '/home/work/data/test5.txt ' into tablestudent_test;

· Copyingdata from File:/home/work/data/test5.txt

· Copyingfile:file:/home/work/data/test5.txt

· Loadingdata to Table Default.student_test

· Ok

· timetaken:0.35 seconds

Inquire:

· Hive>select info.age from Student_test;

· Totalmapreduce jobs = 1

· ......

· Totalmapreduce CPU Time spent:490 msec

· Ok

· 30

· 30

· 20

· 80

· timetaken:21.677 seconds

Array Use
Build table:

· Hive>create table Class_test (name string, Student_id_list array<int>)

· > ROW FORMAT Delimited

· > TERMINATED by ', '

· > COLLECTION ITEMS TERMINATED by ': ';

· Ok

· timetaken:0.099 seconds

Import data:

· $ cattest6.txt

· 034,1:2:3:4

· 035,5:6

· 036,7:8:9:10

· hive> LOAD DATA LOCAL inpath '/home/work/data/test6.txt ' into TABLE class_test;

· Copyingdata from File:/home/work/data/test6.txt

· Copyingfile:file:/home/work/data/test6.txt

· Loadingdata to Table Default.class_test

· Ok

· timetaken:0.198 seconds

Inquire:

· Hive>select student_id_list[3] from Class_test;

· Totalmapreduce jobs = 1

· ......

· Totalmapreduce CPU Time spent:480 msec

· Ok

· 4

· Null

· 10

· timetaken:21.574 seconds

Map Use
Build table:

· Hive>create table employee (ID string, perfmap<string, int>)

· > ROW FORMAT Delimited

· > Fields TERMINATED by ' \ t '

· > COLLECTION ITEMS TERMINATED by ', '

· > MAP KEYS TERMINATED by ': ';

· Ok

· timetaken:0.144 seconds

' Mapkeys TERMINATED by ': KeyValue delimiter

Import data:

· $ cattest7.txt

· 1 job:80,team:60,person:70

· 2 job:60,team:80

· 3 job:90,team:70,person:100

· hive> LOAD DATA LOCAL inpath '/home/work/data/test7.txt ' into TABLE employee;

Inquire:

· Hive>select perf[' person ') from employee;

· Totalmapreduce jobs = 1

· ......

· Totalmapreduce CPU Time spent:460 msec

· Ok

· 70

· Null

· 100

· timetaken:20.902 seconds

· Hive>select perf[' person ') from the employee where perf[' person ' was not null;

· Totalmapreduce jobs = 1

· .......

· Totalmapreduce CPU Time spent:610 msec

· Ok

· 70

· 100

· timetaken:21.989 seconds

· Hive>

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