PostgreSQL 8.2.4 Documentation
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# Chapter 8. Data Types

PostgreSQL has a rich set of native data types available to users. Users may add new types to PostgreSQL using the CREATE TYPE command.

Table 8-1 shows all the built-in general-purpose data types. Most of the alternative names listed in the "Aliases" column are the names used internally by PostgreSQL for historical reasons. In addition, some internally used or deprecated types are available, but they are not listed here.

Table 8-1. Data Types

Name | Aliases | Description
--- | --- | ---
`bigint` | `int8` | signed eight-byte integer
`bigserial` | `serial8` | autoincrementing eight-byte integer
`bit [ (`n`) ]` |  | fixed-length bit string
`bit varying [ (`n`) ]` | `varbit` | variable-length bit string
`boolean` | `bool` | logical Boolean (true/false)
`box` |  | rectangular box in the plane
`bytea` |  | binary data ("byte array")
`character varying [ (`n`) ]` | `varchar [ (`n`) ]` | variable-length character string
`character [ (`n`) ]` | `char [ (`n`) ]` | fixed-length character string
`cidr` |  | IPv4 or IPv6 network address
`circle` |  | circle in the plane
`date` |  | calendar date (year, month, day)
`double precision` | `float8` | double precision floating-point number
`inet` |  | IPv4 or IPv6 host address
`integer` | `int`, `int4` | signed four-byte integer
`interval [ (`p`) ]` |  | time span
`line` |  | infinite line in the plane
`lseg` |  | line segment in the plane
`macaddr` |  | MAC address
`money` |  | currency amount
`numeric [ (`p`, `s`) ]` | `decimal [ (`p`, `s`) ]` | exact numeric of selectable precision
`path` |  | geometric path in the plane
`point` |  | geometric point in the plane
`polygon` |  | closed geometric path in the plane
`real` | `float4` | single precision floating-point number
`smallint` | `int2` | signed two-byte integer
`serial` | `serial4` | autoincrementing four-byte integer
`text` |  | variable-length character string
`time [ (`p`) ] [ without time zone ]` |  | time of day
`time [ (`p`) ] with time zone` | `timetz` | time of day, including time zone
`timestamp [ (`p`) ] [ without time zone ]` |  | date and time
`timestamp [ (`p`) ] with time zone` | `timestamptz` | date and time, including time zone

> Compatibility: The following types (or spellings thereof) are specified by SQL: `bit`, `bit varying`, `boolean`, `char`, `character varying`, `character`, `varchar`, `date`, `double precision`, `integer`, `interval`, `numeric`, `decimal`, `real`, `smallint`, `time` (with or without time zone), `timestamp` (with or without time zone).

Each data type has an external representation determined by its input and output functions. Many of the built-in types have obvious external formats. However, several types are either unique to PostgreSQL, such as geometric paths, or have several possibilities for formats, such as the date and time types. Some of the input and output functions are not invertible. That is, the result of an output function may lose accuracy when compared to the original input.

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