PostgreSQL 8.4.0 Documentation
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# 9.12. Network Address Functions and Operators

Table 9-33 shows the operators available for the `cidr` and `inet` types. The operators `<<`, `<<=`, `>>`, and `>>=` test for subnet inclusion. They consider only the network parts of the two addresses (ignoring any host part) and determine whether one network is identical to or a subnet of the other.

Table 9-33. `cidr` and `inet` Operators

Operator | Description | Example
--- | --- | ---
`<` | is less than | `inet '192.168.1.5' < inet '192.168.1.6'`
`<=` | is 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'`
`>=` | is greater or equal | `inet '192.168.1.5' >= inet '192.168.1.5'`
`>` | is greater than | `inet '192.168.1.5' > inet '192.168.1.4'`
`<>` | is 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'`
`~` | bitwise NOT | `~ inet '192.168.1.6'`
`&` | bitwise AND | `inet '192.168.1.6' & inet '0.0.0.255'`
`|` | bitwise OR | `inet '192.168.1.6' | inet '0.0.0.255'`
`+` | addition | `inet '192.168.1.6' + 25`
`-` | subtraction | `inet '192.168.1.43' - 36`
`-` | subtraction | `inet '192.168.1.43' - inet '192.168.1.19'`

Table 9-34 shows the functions available for use with the `cidr` and `inet` types. The `abbrev`, `host`, and `text` functions are primarily intended to offer alternative display formats.

Table 9-34. `cidr` and `inet` Functions

Function | Return Type | Description | Example | Result
--- | --- | --- | --- | ---
``abbrev`(`inet`)` | `text` | abbreviated display format as text | `abbrev(inet '10.1.0.0/16')` | `10.1.0.0/16`
``abbrev`(`cidr`)` | `text` | abbreviated display format as text | `abbrev(cidr '10.1.0.0/16')` | `10.1/16`
``broadcast`(`inet`)` | `inet` | broadcast address for network | `broadcast('192.168.1.5/24')` | `192.168.1.255/24`
``family`(`inet`)` | `int` | extract family of address; `4` for IPv4, `6` for IPv6 | `family('::1')` | `6`
``host`(`inet`)` | `text` | extract IP address as text | `host('192.168.1.5/24')` | `192.168.1.5`
``hostmask`(`inet`)` | `inet` | construct host mask for network | `hostmask('192.168.23.20/30')` | `0.0.0.3`
``masklen`(`inet`)` | `int` | extract netmask length | `masklen('192.168.1.5/24')` | `24`
``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`
``set_masklen`(`inet`, `int`)` | `inet` | set netmask length for `inet` value | `set_masklen('192.168.1.5/24', 16)` | `192.168.1.5/16`
``set_masklen`(`cidr`, `int`)` | `cidr` | set netmask length for `cidr` value | `set_masklen('192.168.1.0/24'::cidr, 16)` | `192.168.0.0/16`
``text`(`inet`)` | `text` | extract IP address and netmask length as text | `text(inet '192.168.1.5')` | `192.168.1.5/32`

Any `cidr` value can be cast to `inet` implicitly or explicitly; therefore, the functions shown above as operating on `inet` also work on `cidr` values. (Where there are separate functions for `inet` and `cidr`, it is because the behavior should be different for the two cases.) Also, it is permitted to cast an `inet` value to `cidr`. When this is done, any bits to the right of the netmask are silently zeroed to create a valid `cidr` value. In addition, you can cast a text value to `inet` or `cidr` using normal casting syntax: for example, `inet(`expression`)` or ``colname`::cidr`.

Table 9-35 shows the functions available for use with the `macaddr` type. The function ``trunc`(`macaddr`)` returns a MAC address with the last 3 bytes set to zero. This can be used to associate the remaining prefix with a manufacturer.

Table 9-35. `macaddr` Functions

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

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