String Data Types

PostgreSQL includes three basic data types for storing string-related data. In compliance with the SQL standard, there are types for fixed-length and variable-length character strings. Additionally, PostgreSQL defines a more generic data type named TEXT that requires no specified upper limit regarding maximum size. However, this data type is PostgreSQL-specific and is not compliant with the SQL-92 standards.

CHAR (or CHARACTER)

Description

Holds a fixed-length string specified with a maximum length.

Inputs

CHAR(n) 

n—Integer length of string (if omitted, a 1 is assumed).

Storage Size

(4+n) bytes

Notes

CHAR is a SQL-92-compatible data type. Data that does not fill to the limit specified is blank padded.

TEXT

Description

Holds a variable-length string.

Storage Size

Variable—depends on the length of string, but no smaller than 4 bytes.

VARCHAR (or CHARACTER VARYING)

Description

Holds a variable-length string with a specified limit.

Inputs

VARCHAR(n) 

n—Integer length of string (if omitted, a 1 is assumed).

Storage Size

Variable—depends on the length of string, but no smaller than 4 bytes.

Notes

VARCHAR and CHARACTER VARYING are both SQL-compatible data types.