Data Types

Data Types

Boolean Data

  • TRUE

  • FALSE

  • NULL

TRUE
FALSE

TRUE

FALSE

'true'

'false'

't'

'f'

'yes'

'no'

'y'

'n'

'1'

'0'

CREATE TABLE booltable (
    id SERIAL PRIMARY KEY ,
    is_enable BOOLEAN NOT NULL
);

INSERT INTO booltable (is_enable) VALUES (TRUE), ('true'), 
    ('y') , ('yes'), ('t'), ('1');
INSERT INTO booltable (is_enable) VALUES (FALSE), ('false'), 
    ('n') , ('no'), ('f'), ('0');

SELECT * FROM booltable;

SELECT * FROM booltable WHERE is_enable = 'y';

SELECT * FROM booltable WHERE NOT is_enable;

Character Data

Character Type
Notes

CHARACTER (N), CHAR (N)

fixed-length, blank padded

CHARACTER VARYING (N), VARCHAR(N)

variable length with length limit

TEXT, VARCHAR

variable unlimited length, max 1GB

  • n is default to 1

-- INPUT
SELECT CAST('Uday' as character(10)) as "name";
-- OUTPUT
"Uday      "

-- INPUT
SELECT 'Uday'::character(10) as "name";
-- OUTPUT
"Uday      "

-- INPUT
SELECT 'uday'::varchar(10);
-- OUTPUT
"uday"

-- INPUT
SELECT 'lorem ipsum'::text;
-- OUTPUT
"lorem ipsum"

Numeric Data

Types
Notes

Integers

whole number, +ve and -ve

Fixed-point, floating point

for fractions of whole nu

type
size (bytes)
min
max

smallint

2

-32678

32767

integer

4

-2,147,483,648

2,147,483,647

bigint

8

-9223372036854775808

9223372036854775807

type
size
range

smallserial

2

1 to 32767

serial

4

1 to 2147483647

bigserial

8

1 to 9223372036854775807

Fixed Point Data

numeric ( precision , scale ) | decimal ( precision , scale )

  • precision : max number of digits to the left and right of the decimal point

  • scale : number of digits allowable on the right of the decimal point

Floating Point Data

Type
Notes

Real

allows precision to six decimal digits

Double precision

allows precision to 15 digits points of precision

type
size
storage type
Range

numeric, decimal

variable

fixed point

131072 digits before decimal point and 16383 digits after the decimal point

real

4

floating point

6 decimal digits precision

double precision

8

floating point

15 decimal digits precision

CREATE TABLE table_numbers (
    col_numeric numeric(20,5),
    col_real real,
    col_double double precision
);

INSERT INTO table_numbers (col_numeric,col_real,col_double)
VALUES (.9,.9,.9),
       (3.34675,3.34675,3.34675),
       (4.2345678910,4.2345678910,4.2345678910);

SELECT * FROM table_numbers;

-- OUTPUT
learning=# select * from table_numbers ;
 col_numeric | col_real | col_double  
-------------+----------+-------------
     0.90000 |      0.9 |         0.9
     3.34675 |  3.34675 |     3.34675
     4.23457 | 4.234568 | 4.234567891
(3 rows)

Hierarchical order to SELECT best type : numeric > decimal > float

Date Time Data

type
stores
low
high

Date

date only

4713 BC

294276 AD

Time

time only

4713 BC

5874897 AD

Timestamp

date and time

4713 BC

294276 AD

Timestampz

date, time and timezone

4713 BC

294276 AD

Interval

difference btw time

Date type

CREATE TABLE table_dates (
    id serial primary key,
    employee_name varchar(100) not null,
    hire_date DATE NOT NULL,
    add_date DATE DEFAULT CURRENT_DATE
);

INSERT INTO table_dates (employee_name, hire_date)
    VALUES ('uday','2020-02-02'),('another uday','2020-02-01');

SELECT *
FROM table_dates;

SELECT NOW();

Time type

CREATE TABLE table_time (
    id serial primary key ,
    class_name varchar(10) not null ,
    start_time time not null ,
    end_time time not null
);

INSERT INTO table_time (class_name, start_time, end_time) 
    VALUES ('maths','08:00:00','08:55:00'),
           ('chemistry','08:55:00','09:00:00');

SELECT * FROM table_time;

-- OUTPUT

 id | class_name | start_time | end_time 
----+------------+------------+----------
  1 | maths      | 08:00:00   | 08:55:00
  2 | chemistry  | 08:55:00   | 09:00:00
(2 rows)


SELECT CURRENT_TIME;

    current_time    
--------------------
 07:21:00.163354+00
(1 row)


SELECT CURRENT_TIME(2);

  current_time  
----------------
 07:21:14.96+00
(1 row)


SELECT LOCALTIME;

    localtime    
-----------------
 07:21:36.717509
(1 row)


SELECT time '12:10' - time '04:30' as RESULT;
  result  
----------
 07:40:00
(1 row)


-- format : interval 'n type'
-- n = number
-- type : second, minute, hours, day, month, year ....

SELECT CURRENT_TIME ,
    CURRENT_TIME + INTERVAL '2 hours' as RESULT;

    current_time    |       result       
--------------------+--------------------
 07:22:06.241919+00 | 09:22:06.241919+00
(1 row)


SELECT CURRENT_TIME ,
    CURRENT_TIME + INTERVAL '-2 hours' as RESULT;

    current_time    |       result       
--------------------+--------------------
 07:22:16.644727+00 | 05:22:16.644727+00
(1 row)

Timestamp and Timezone

  • timestamp : stores time without time zone

  • timestamptz : timestamp with time zone , stored using UTC format

  • adding timestamp to timestamptz without mentioning the zone will result in server automatically assumes timezone to system's timezone

  • Internally, PostgreSQL will store the timezoneaccurately but then OUTPUTting the data, will it be converted according to your timezone

SELECT name FROM pg_timezone_names 
    where name = 'posix/Asia/Calcutta';

SET TIMEZONE='Asia/Calcutta';

SELECT NOW()::TIMESTAMP;

            now             
----------------------------
 2021-08-12 12:53:03.971433
(1 row)


CREATE TABLE table_time_tz (
    ts timestamp,
    tstz timestamptz
);

INSERT INTO table_time_tz (ts, tstz) 
    VALUES ('2020-12-22 10:10:10',
            '2020-12-22 10:10:10.009+05:30');

SELECT * FROM table_time_tz;

         ts          |             tstz              
---------------------+-------------------------------
 2020-12-22 10:10:10 | 2020-12-22 10:10:10.009+05:30
(1 row)


SELECT CURRENT_TIMESTAMP;

        current_timestamp        
---------------------------------
 2021-08-12 12:53:29.54762+05:30
(1 row)


SELECT timezone('Asia/Singapore','2020-01-01 00:00:00')

      timezone       
---------------------
 2020-01-01 02:30:00
(1 row)

UUID

  • UUID : Universal Unique Identifier

  • PostgreSQL doesn't provide internal function to generate UUID's, use uuid-ossp

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

SELECT uuid_generate_v1();

           uuid_generate_v1           
--------------------------------------
 4d459e0c-fb3e-11eb-a638-0242ac110002


-- pure randomness
SELECT uuid_generate_v4();

           uuid_generate_v4           
--------------------------------------
 418f39e5-8a46-4da2-8cea-884904f45d6f


CREATE TABLE products_uuid (
    id uuid default uuid_generate_v1(),
    product_name varchar(100) not null
);

INSERT INTO products_uuid (product_name) 
    VALUES ('ice cream'),('cake'),('candies');

SELECT * FROM products_uuid;

                  id                  | product_name 
--------------------------------------+--------------
 5cf1dbe0-fb3e-11eb-a638-0242ac110002 | ice cream
 5cf1df28-fb3e-11eb-a638-0242ac110002 | cake
 5cf1df46-fb3e-11eb-a638-0242ac110002 | candies

CREATE TABLE products_uuid_v4 (
    id uuid default uuid_generate_v4(),
    product_name varchar(100) not null
);

INSERT INTO products_uuid_v4 (product_name) 
    VALUES ('ice cream'),('cake'),('candies');

SELECT * FROM products_uuid_v4;

learning=# SELECT * FROM products_uuid_v4;
                  id                  | product_name 
--------------------------------------+--------------
 83b74bed-2cf8-4e26-80b0-c7c7b2e5f3e7 | ice cream
 ac563251-7a95-408d-966b-ed5ecc1f228d | cake
 1079f6d3-b0c3-40ef-bd2e-da4467b63432 | candies

HSTORE

  • stores data in key-value pairs

  • key and VALUES are text string only

CREATE EXTENSION IF NOT EXISTS hstore;

CREATE TABLE table_hstore (
    id SERIAL PRIMARY KEY ,
    title varchar(100) not null,
    book_info hstore
);

INSERT INTO table_hstore (title, book_info) VALUES
(
    'Title 1', ' "publisher" => "ABC publisher" , 
    "paper_cost" => "100" , "e_cost" => "5.85" '
);

SELECT * FROM table_hstore;

 id |  title  |   book_info                              

  1 | Title 1 | "e_cost"=>"5.85", "publisher"=>"ABC publisher", "paper_cost"=>"100"


SELECT book_info -> 'publisher' as publisher 
FROM table_hstore;

   publisher   
---------------
 ABC publisher

Json

  • PostgreSQL supports both

    • JSON

    • BSON or JSONB ( Binary JSON )

  • JSONB has full support for indexing

CREATE TABLE table_json (
    id SERIAL PRIMARY KEY ,
    docs json
);

INSERT INTO table_json (docs) 
    VALUES ('[1,2,3,4,5,6]'),('{"key":"value"}');

INSERT INTO table_json (docs)
VALUES ('[{"key":"value"},{"key2":"value2"}]');

SELECT * FROM table_json;

 id |                docs                 
----+-------------------------------------
  1 | [1,2,3,4,5,6]
  2 | {"key":"value"}
  3 | [{"key":"value"},{"key2":"value2"}]


ALTER TABLE table_json alter column docs type jsonb;

SELECT * FROM table_json where docs @> '2';

 id |        docs        
----+--------------------
  1 | [1, 2, 3, 4, 5, 6]


CREATE index on table_json USING GIN (docs jsonb_path_ops);

Network Address Data Types

Name
Storage Size
Notes

cidr

7 or 19 bytes

IPv4 and IPv6 networks

inet

7 or 19 bytes

IPv4 and IPv6 hosts and networks

macaddr

6 bytes

MAC addresses

macaddr8

8 bytes

MAC addresses ( EUI 64-bit )

  • It is better to use these types instead of plain text types of store network address, because these types offer input error checking and specialised operators and functions

  • Supports indexing and advance operations

CREATE TABLE table_netaddr (
    id SERIAL PRIMARY KEY ,
    ip inet
);

INSERT INTO table_netaddr (ip)
VALUES ('148.77.50.74'),
        ('110.158.172.66'),
        ('176.103.251.175'),
        ('84.84.14.58'),
        ('141.122.225.161'),
        ('78.44.113.33'),
        ('81.236.254.9'),
        ('82.116.85.21'),
        ('54.64.79.223'),
        ('162.240.78.253');

SELECT * FROM table_netaddr LIMIT 5;

 id |       ip        
----+-----------------
  1 | 148.77.50.74
  2 | 110.158.172.66
  3 | 176.103.251.175
  4 | 84.84.14.58
  5 | 141.122.225.161


SELECT 
       ip, 
       set_masklen(ip,24) as inet_24, 
       set_masklen(ip::cidr,24) as cidr_24 ,
       set_masklen(ip::cidr,27) as cidr_27,
       set_masklen(ip::cidr,28) as cidr_28 
FROM 
     table_netaddr LIMIT 2;

 ip | inet_24 | cidr_24 | cidr_27 | cidr_28 

 148.77.50.74   | 148.77.50.74/24   | 148.77.50.0/24   | 148.77.50.64/27   | 148.77.50.64/28
 110.158.172.66 | 110.158.172.66/24 | 110.158.172.0/24 | 110.158.172.64/27 | 110.158.172.64/28
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