Data types in Hive
Data types are very important elements in Hive query language and data modeling. For defining the table column types, we must have to know about the data types and its usage.
The following gives brief overview of some data types present in Hive:
These are
- Numeric Types
- String Types
- Date/Time Types
- Complex Types
Numeric Types:
| Type | Memory allocation |
| TINY INT | Its 1-byte signed integer (-128 to 127) |
| SMALL INT | 2-byte signed integer (-32768 to 32767) |
| INT | 4 –byte signed integer ( -2,147,484,648 to 2,147,484,647) |
| BIG INT | 8 byte signed integer |
| FLOAT | 4 – byte single precision floating point number |
| DOUBLE | 8- byte double precision floating point number |
| DECIMAL | We can define precision and scale in this Type |
String Types:
| Type | Length |
| CHAR | 255 |
| VARCHAR | 1 to 65355 |
| STRING | We can define length here(No Limit) |
Date/Time Types:
| Type | Usage |
| Timestamp | Supports traditional Unix timestamp with optional nanosecond precision |
| Date |
|
Complex Types:
| Type | Usage |
| Arrays | ARRAY<data_type> Negative values and non-constant expressions not allowed |
| Maps | MAP<primitive_type, data_type> Negative values and non-constant expressions not allowed |
| Structs | STRUCT<col_name :datat_type, ….. > |
| Union | UNIONTYPE<data_type, datat_type, ……> |
Creation and dropping of Database in Hive:
Create Database:
For creating database in Hive shell, we have to use the command as shown in syntax below:-
Syntax:
Create database <DatabaseName>
Example: -Create database "guru99"
From the above screen shot, we are doing two things
- Creating database "guru99" in Hive
- Displaying existing databases using "show" command
- In the same screen, Database "guru99" name is displayed at the end when we execute the show command. Which means Database "guru99" is successfully created.
Drop Database:
For Dropping database in Hive shell, we have to use the "drop" command as shown in syntax below:-
Syntax:
Drop database <DatabaseName>
Example:-
Drop database guru99
In the above screenshot, we are doing two things
- We are dropping database 'guru99' from Hive
- Cross checking the same with "show" command
- In the same screen, after checking databases with show command, database"guru99" does not appear inside Hive.
- So we can confirm now that database "guru99" is dropped
