PostgreSQL Data Types

Time/ Time with Time Zone Input

Boolean Type

A Boolean data type can hold

• True
• False
• null

values.

You use a bool or boolean keyword to declare a column with the Boolean data type.

When you insert values into a boolean column, Postgre converts values like

• Yes
• y
• 1
• t
• true

into 1.

While values like

• No
• N
• 0
• F
• False

are converted to 0

While selecting data, the values are again converted back to yes, true, y, etc.

Geometric Data Types

Geometric data types represent two-dimensional spatial objects. They help perform operations like rotations, scaling, translation, etc.

Enumerated Types

Enumerated Data types in PostgreSQL is useful for representing rarely changing information such as country code or branch id. The Enumerated data type is represented in a table with foreign keys to ensure data integrity.

Example:

Hair color is fairly static in a demographic database

CREATE TYPE hair_color AS ENUM
('brown','black','red','grey','blond')

Range Type

Many business applications require data in ranges. Typically, two columns (example: start date, end date) are defined to deal with ranges. This is both inefficient and difficult to maintain.

Postgre has built range types as follows

• int4range — Display range of integer
• int8range — Display range of bigint
• numrange — Shows the numeric range
• tstrange — Helps you to display timestamp without time zone
• strange — Allows you to display timestamp with time zone
• date range — Range of date

UUID type

Universally Unique Identifies (UUID) is a 128-bit quantity which is generated by an algorithm. It is very unlikely that the same identifier will be generated by another person in the world using the same algorithm. That’s why for the distributed systems, these identifiers are an ideal choice as it offers uniqueness within a single database. A UUID is written as a group of lower-case hexadecimal digits, with various groups separated by hyphens.

PostgreSQL has a native UUID data type which consumes 16 bytes of storage.. UUID is an ideal Data type for primary keys.

Example:

d5f28c97-b962-43be-9cf8-ca1632182e8e

Postgre also accepts alternative forms of UUID inputs like all capital case, no hyphens, braces, etc.

XML type

PostgreSQL allows you to store XML data in a data type, but it is nothing more than an extension to a text data type. But the advantage is that it checks that the input XML is well-formed.

Example:

XMLPARSE (DOCUMENT '<?xml version="1.0"?><tutorial><chapter>Data Type</chapter><chapter>...</chapter></tutorial>')

JSON Type

To store JSON data PostgreSQL offers 2 data types

1. JSON
2. JSONB

Most widely used JSON data type used us jsonb unless there is some specialized need to use JSON data type.

Example:

CREATE TABLE employee (
  id integer NOT NULL,
  age  integer NOT NULL,
  data jsonb
);

INSERT INTO employee VALUES (1, 35, '{"name": "Tom Price", "tags": ["Motivated", "SelfLearner"], "onboareded": true}'); 

Pseudo-Types

PostgreSQL has many special-purpose entries that are called pseudo-types. You can’t use pseudo-type as a column data type. There are used to declare or function’s argument or return type.

Each of the available pseudo-types is helpful in situations where a function’s behavior docs do not correspond to simply taking or returning a value of a specific SQL data type.

It is important that the user who is using this function need to make sure that the function will behave securely when a pseudo-type is used as an argument type.

Best practices using Data types

• Use “text” data type unless you want to limit the input
• Never use “char.”
• Integers use “int.” Use bigint only when you have really big numbers
• Use “numeric” almost always
• Use float data type if you have IEEE 754 data source

Summary

• PostgreSQL offers a rich set of native data types for users
• PostgreSQL supports character data types for storing text values
• PostgreSQL supports two distinct types of numbers: 1. Integers, 2. Floating-point numbers
• A binary string is a sequence of bytes or octets
• PostgreSQL has Network address type help you to optimize storage of network data
• Text search data types are designed to support full-text search
• Date/Time data types are allow date and time information in various formats
• A Boolean data type can hold three values 1. True 2. False 3. Null
• Geometric data types represent two-dimensional spatial objects
• Enumerated Data types in PostgreSQL is useful for representing rarely changing information such as country code or branch id
• Universally Unique Identifies (UUID) is a 128-bit quantity which is generated by an algorithm
• PostgreSQL has many special-purpose entries that are called pseudo-types
• It is best practice to use “text” data type unless you want to limit the input