PostgreSQL 7.2.1 Documentation
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# 4.10. Network Address Type Functions

Table 4-21. `cidr` and `inet` Operators

Operator | Description | Usage
--- | --- | ---
< | Less than | `inet '192.168.1.5' < inet '192.168.1.6'`
<= | Less than or equal | `inet '192.168.1.5' <= inet '192.168.1.5'`
= | Equals | `inet '192.168.1.5' = inet '192.168.1.5'`
>= | Greater or equal | `inet '192.168.1.5' >= inet '192.168.1.5'`
> | Greater | `inet '192.168.1.5' > inet '192.168.1.4'`
<> | Not equal | `inet '192.168.1.5' <> inet '192.168.1.4'`
<< | is contained within | `inet '192.168.1.5' << inet '192.168.1/24'`
<<= | is contained within or equals | `inet '192.168.1/24' <<= inet '192.168.1/24'`
>> | contains | `inet'192.168.1/24' >> inet '192.168.1.5'`
>>= | contains or equals | `inet '192.168.1/24' >>= inet '192.168.1/24'`

All of the operators for `inet` can be applied to `cidr` values as well. The operators `<<`, `<<=`, `>>`, `>>=` test for subnet inclusion: they consider only the network parts of the two addresses, ignoring any host part, and determine whether one network part is identical to or a subnet of the other.

Table 4-22. `cidr` and `inet` Functions

Function | Returns | Description | Example | Result
--- | --- | --- | --- | ---
`broadcast`(`inet`) | `inet` | broadcast address for network | `broadcast('192.168.1.5/24')` | `192.168.1.255/24`
`host`(`inet`) | `text` | extract IP address as text | `host('192.168.1.5/24')` | `192.168.1.5`
`masklen`(`inet`) | `integer` | extract netmask length | `masklen('192.168.1.5/24')` | `24`
`set_masklen`(`inet`,`integer`) | `inet` | set netmask length for inet value | `set_masklen('192.168.1.5/24',16)` | `192.168.1.5/16`
`netmask`(`inet`) | `inet` | construct netmask for network | `netmask('192.168.1.5/24')` | `255.255.255.0`
`network`(`inet`) | `cidr` | extract network part of address | `network('192.168.1.5/24')` | `192.168.1.0/24`
`text`(`inet`) | `text` | extract IP address and masklen as text | `text(inet '192.168.1.5')` | `192.168.1.5/32`
`abbrev`(`inet`) | `text` | extract abbreviated display as text | `abbrev(cidr '10.1.0.0/16')` | `10.1/16`

All of the functions for `inet` can be applied to `cidr` values as well. The `host`(), `text`(), and `abbrev`() functions are primarily intended to offer alternative display formats. You can cast a text field to inet using normal casting syntax: `inet(expression)` or `colname::inet`.

Table 4-23. `macaddr` Functions

Function | Returns | Description | Example | Result
--- | --- | --- | --- | ---
`trunc`(`macaddr`) | `macaddr` | set last 3 bytes to zero | `trunc(macaddr '12:34:56:78:90:ab')` | `12:34:56:00:00:00`

The function `trunc`(`macaddr`) returns a MAC address with the last 3 bytes set to 0. This can be used to associate the remaining prefix with a manufacturer. The directory `contrib/mac` in the source distribution contains some utilities to create and maintain such an association table.

The `macaddr` type also supports the standard relational operators (`>`, `<=`, etc.) for lexicographical ordering.

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