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Hadoop Hive Data Types with Examples
Data Types
HIVE supports many of the Primitive Data types you find in relational databases.
Primitive Data types
- Hive supports several sizes of integer and floating point types, a Boolean type and character strings of arbitress length.
- Hive v 0.8.0 added types of time stamps and binary fields.
Primitive types supported by Hive are:
|
Type |
Size |
Example |
|
Tiny int |
1 byte signed integer |
20 |
|
Small Int |
2 byte signed integer |
20 |
|
INT |
4 byte signed integer |
20 |
|
BIGINT |
8 byte signed integer |
20 |
|
BOOLEAN |
Boolean true or false |
TRUE |
|
FLOAT |
Single Precision floating point |
3.14159 |
|
DOUBLE |
Double precision floating point |
3.14159 |
|
STRING |
Sequence of characters single or Double quotes can be used |
‘Now is the hme’,”for all good my” |
Collection Data Types:-
Hive supports columns that are struct, maps and arrays
|
Type |
Description |
Example |
|
STRUCT |
Analogous to a (struct or an “object” fields can be accessed) using the ”dot” nation. For example, if a column name of type STRUCT {first string, last string} then the first name field can be referenced using name first |
Struct(‘Joint’,’Doe’) |
|
MAP |
A collection of key-value resples, where the fields are accessed using array notation (e.g[“key”]). For example, if a column name is of type MAP with key |
map(‘first’, ’join’, ’last’, ’Doe’) |
|
ARRAY |
Ordered sequences of the same type that are inferable using zero-based integers. |
Array(‘John’,’Doe’) |
Text File Encoding:
Text files are delimited with commas or tabs which are called CSV’s or TSR’s respectively.
Hive can use those formats but there is a draw back to both formats.
- We have to be careful about commas or tabs embedded in text and not intended as field or column delimiters.
- For this reason, Hive uses various control characters by default, which are less likely to appear in value strings.
Hive uses the term field when overriding the default delimiter.
|
Delimiter |
Description |
|
|
For text files, each line is a record so the line feed character separates records. |
|
^ A |
Separates all fields (Columns) and written using the octal code ?01 cohen explicitly specified in CREATE TABLE Statements. |
|
^ B |
Separate the elements in an ARRAY or STRUCT, or the key-value paid in a MAP written using the octal code?02 when explicitly specified in CREATE TABLE Statements. |
|
^ C |
Separate the key from the corresponding value |
Overriding default delimiters:-
Table deduction with all the format defaults explicitly specified.
CREATE TABLE Employees(name STRING, Salary FLOAT, Subordinates ARRAY< STRING >Deduction MAP< STRING, FLOAT>, Address STRUCT )
ROW FORMAT DELIMITED FIELDS TERNNATED
- By’?01’ COLLECTION ITEMS TERMINATED
- By’?02’ MAP KEYS TERMINATED By’?03’
LINES TERMINATED By’n’ STORED AS TEXT FILE; ROW FORMAT DELIMITED.
- Sequence of key words must appear before any of the other clauses, with the exception of the STORED AS –Clause.
- ?01 is the octal code for ^ A character to separate fields.
- Similarly, /002 is the octal code for ^ B and /003 B the octal code for ^ C
- Hive uses the ^B character to separate collection items and ^C character to separate map keys from values.
- The clause LINES TERMINATED By() and STORED AS-do not requite the ROW FORMAT DELIMITED Keywords.
EX : Text File for the Table created as above:-
- John Doc ^A100000.0 ^A May smith ^B Todd. Jones ^A Fedoral Taxes^C.2
- ^B State Taxes ^C.05 ^B Insurance ^C.1^A1 Michigan Are. ^B chicage ^BIL ^B 606
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