PostgreSQL Data Types

• This chapter discusses PostgreSQL Data Types While creating table, for each column, you specify a data type, i.e., what kind of data you want to store in the table fields.
• There are different categories of data types in PostgreSQL. They are discussed as below:

Numeric datatype:

• Numeric types consist of two-, four-, and eight-byte integers, four- and eight-byte floating-point numbers, and selectable-precision decimals. 

Name	Storage Size	Description	Range
smallint	2 bytes	small-range integer	-32768 to +32767
integer	4 bytes	typical choice for integer	-2147483648 to +2147483647
bigint	8 bytes	large-range integer	-9223372036854775808 to +9223372036854775807
decimal	variable	user-specified precision, exact	up to 131072 digits before the decimal point; up to 16383 digits after the decimal point
numeric	variable	user-specified precision, exact	up to 131072 digits before the decimal point; up to 16383 digits after the decimal point
real	4 bytes	variable-precision, inexact	6 decimal digits precision
Double precision	8 bytes	variable-precision, inexact	15 decimal digits precision
smallserial	2 bytes	small autoincrementing integer	1 to 32767
serial	4 bytes	autoincrementing integer	1 to 2147483647
bigserial	8 bytes	large autoincrementing integer	1 to 9223372036854775807

Monetary Types:

• The money type stores a currency amount with a fixed fractional precision; 
• The fractional precision is determined by the database's lc_monetary setting. The range shown in the table assumes there are two fractional digits. Input is accepted in a variety of formats, including integer and floating-point literals, as well as typical currency formatting, such as '$1,000.00'. Output is generally in the latter form but depends on the locale.

Name	Storage Size	Description	Range
money	8 bytes	currency amount	-92233720368547758.08 to +92233720368547758.07

Character Types:

• The table below lists general-purpose character types available in PostgreSQL.

Name	Description
character varying(n), varchar(n)	variable-length with limit
character(n), char(n)	fixed-length, blank padded
text	variable unlimited length

Binary Data Types:

• The bytea data type allows storage of binary strings

Name	Storage Size	Description
bytea	1 or 4 bytes plus the actual binary string	variable-length binary string

Date/Time Types:

• PostgreSQL supports the full set of SQL date and time types, 
• Dates are counted according to the Gregorian calendar, even in years before that calendar was introduced 

Name	Storage Size	Description	Low Value	High Value	Resolution
timestamp [ (p) ] [ without time zone ]	8 bytes	both date and time (no time zone)	4713 BC	294276 AD	1 microsecond / 14 digits
timestamp [ (p) ] with time zone	8 bytes	both date and time, with time zone	4713 BC	294276 AD	1 microsecond / 14 digits
date	4 bytes	date (no time of day)	4713 BC	5874897 AD	1 day
time [ (p) ] [ without time zone ]	8 bytes	time of day (no date)	00:00:00	24:00:00	1 microsecond / 14 digits
time [ (p) ] with time zone	12 bytes	times of day only, with time zone	00:00:00+1459	24:00:00-1459	1 microsecond / 14 digits
interval [ fields ] [ (p) ]	16 bytes	time interval	-178000000 years	178000000 years	1 microsecond / 14 digits

Boolean Type:

• PostgreSQL provides the standard SQL type boolean; 
• The boolean type can have several states: "true", "false", and a third state, "unknown", which is represented by the SQL null value.

Name	Storage Size	Description
boolean	1 byte	state of true or false

Valid literal values for the "true" state are:
TRUE
't'
'true'
'y'
'yes'
'on'
'1'
For the "false" state, the following values can be used:
FALSE
'f'
'false'
'n'
'no'
'off'
'0'

Leading or trailing whitespace is ignored, and case does not matter. The key words TRUE and FALSE are the preferred (SQL-compliant) usage.

Enumerated Types:

• Enumerated (enum) types are data types that comprise a static, ordered set of values. They are equivalent to the enum types supported in a number of programming languages. 
• An example of an enum type might be the days of the week, or a set of status values for a piece of data.

Examples:

CREATE TYPE mood AS ENUM ('sad', 'ok', 'happy');
CREATE TABLE person (
    name text,
    current_mood mood
);

INSERT INTO person VALUES ('Moe', 'happy');
SELECT * FROM person WHERE current_mood = 'happy';
 name | current_mood 
------+--------------
 Moe  | happy
(1 row)

Geometric Types:

• Geometric data types represent two-dimensional spatial objects
• A rich set of functions and operators is available to perform various geometric operations such as scaling, translation, rotation, and determining intersections

Name	Storage Size	Description	Representation
point	16 bytes	Point on a plane	(x,y)
line	32 bytes	Infinite line	{A,B,C}
lseg	32 bytes	Finite line segment	((x1,y1),(x2,y2))
box	32 bytes	Rectangular box	((x1,y1),(x2,y2))
path	16+16n bytes	Closed path (similar to polygon)	((x1,y1),...)
path	16+16n bytes	Open path	[(x1,y1),...]
polygon	40+16n bytes	Polygon (similar to closed path)	((x1,y1),...)
circle	24 bytes	Circle	<(x,y),r> (center point and radius)

Network Address Types:

• PostgreSQL offers data types to store IPv4, IPv6, and MAC addresses. 
• It is better to use these types instead of plain text types to store network addresses, because these types offer input error checking and specialized operators and functions

Name	Storage Size	Description
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

Bit String Type:

• Bit String Types are used to store bit masks. They are either 0 or 1. There are two SQL bit types: bit(n) and bit varying(n), where n is a positive integer.

Text Search Types:

• PostgreSQL provides two data types that are designed to support full text search, which is the activity of searching through a collection of natural-language documents to locate those that best match a query. 
• The tsvector type represents a document in a form optimized for text search; 
• the tsquery type similarly represents a text query. 

UUID Types:

• A UUID (Universally Unique Identifiers) is written as a sequence of lower-case hexadecimal digits,
• In several groups separated by hyphens, specifically a group of 8 digits followed by three groups of 4 digits followed by a group of 12 digits, for a total of 32 digits representing the 128 bits.

Example:ba0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11

XML Types

• The xml data type can be used to store XML data. Its advantage over storing XML data in a text field is that it checks the input values for well-formedness, 
•  There are support functions to perform type-safe operations on it;. 
• Use of this data type requires the installation to have been built with configure --with-libxml.

JSON Types:

• JSON data types are for storing JSON (JavaScript Object Notation) data, as specified in RFC 7159. 
• Such data can also be stored as text, but the JSON data types have the advantage of enforcing that each stored value is valid according to the JSON rules. 
• There are also assorted JSON-specific functions and operators available for data stored in these data types

JSON primitive types and corresponding PostgreSQL types

JSON primitive type	PostgreSQL type	Notes
string	text	\u0000 is disallowed, as are non-ASCII Unicode escapes if database encoding is not UTF8
number	numeric	NaN and infinity values are disallowed
boolean	boolean	Only lowercase true and false spellings are accepted
null	(none)	SQL NULL is a different concept

Arrays Types:

• PostgreSQL allows columns of a table to be defined as variable-length multidimensional arrays. Arrays of any built-in or user-defined base type, enum type, or composite type can be created. Arrays of domains are not yet supported.

Composite Types:

• A composite type represents the structure of a row or record; it is essentially just a list of field names and their data types.
•  PostgreSQL allows composite types to be used in many of the same ways that simple types can be used. 
• For example, a column of a table can be declared to be of a composite type.

Range Types:

• Range types are data types representing a range of values of some element type (called the range's subtype). For instance, ranges of timestamp might be used to represent the ranges of time that a meeting room is reserved. In this case the data type is tsrange (short for "timestamp range"), and timestamp is the subtype. The subtype must have a total order so that it is well-defined whether element values are within, before, or after a range of values.
• Range types are useful because they represent many element values in a single range value, and because concepts such as overlapping ranges can be expressed clearly. 
• The use of time and date ranges for scheduling purposes is the clearest example; but price ranges, measurement ranges from an instrument, and so forth can also be useful.

PostgreSQL comes with the following built-in range types:

int4range — Range of integer

int8range — Range of bigint

numrange — Range of numeric

tsrange — Range of timestamp without time zone

tstzrange — Range of timestamp with time zone

daterange — Range of date

Object Identifier Types:

• Object identifiers (OIDs) are used internally by PostgreSQL as primary keys for various system tables. 
• OIDs are not added to user-created tables, unless WITH OIDS is specified when the table is created, or the default_with_oids configuration variable is enabled. 
• Type oid represents an object identifier. There are also several alias types for oid: regproc, regprocedure, regoper, regoperator, regclass, regtype, regrole, regnamespace, regconfig, and regdictionary

pg_lsn Type:

• The pg_lsn data type can be used to store LSN (Log Sequence Number) data which is a pointer to a location in the XLOG. 
• This type is a representation of XLogRecPtr and an internal system type of PostgreSQL.
• Internally, an LSN is a 64-bit integer, representing a byte position in the write-ahead log stream. It is printed as two hexadecimal numbers of up to 8 digits each, separated by a slash; for example, 16/B374D848. The pg_lsn type supports the standard comparison operators, like = and >. Two LSNs can be subtracted using the - operator; the result is the number of bytes separating those write-ahead log positions.

Pseudo-Types:

• The PostgreSQL type system contains a number of special-purpose entries that are collectively called pseudo-types. 
• A pseudo-type cannot be used as a column data type, but it can be used to declare a function's argument or result type. Each of the available pseudo-types is useful in situations where a function's behavior does not correspond to simply taking or returning a value of a specific SQL data type

Name	Description
any	Indicates that a function accepts any input data type.
anyelement	Indicates that a function accepts any data type
anyarray	Indicates that a function accepts any array data type
anynonarray	Indicates that a function accepts any non-array data type
anyenum	Indicates that a function accepts any enum data type
anyrange	Indicates that a function accepts any range data type
cstring	Indicates that a function accepts or returns a null-terminated C string.
internal	Indicates that a function accepts or returns a server-internal data type.
language_handler	A procedural language call handler is declared to return language_handler.
fdw_handler	A foreign-data wrapper handler is declared to return fdw_handler.
tsm_handler	A tablesample method handler is declared to return tsm_handler.
record	Identifies a function taking or returning an unspecified row type.
trigger	A trigger function is declared to return trigger.
event_trigger	An event trigger function is declared to return event_trigger.
pg_ddl_command	Identifies a representation of DDL commands that is available to event triggers.
void	Indicates that a function returns no value.
opaque	An obsolete type name that formerly served all the above purposes.

Postgres Domain Data Type:

• user-defined data type with a range, optional DEFAULT, NOT NULL and CHECK constraint.
• domain will be check faster than primary key  you will understand from Domain Data Type Example