PostgreSQL 7.4 Documentation
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# 9.10. Network Address Type Functions

Table 9-31 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 part is identical to or a subnet of the other.

Table 9-31. `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'

Table 9-32 shows the functions available for use with the `cidr` and `inet` types. The `host`, `text`, and `abbrev` functions are primarily intended to offer alternative display formats. You can cast a text value to `inet` using normal casting syntax: inet(expression) or colname::inet.

Table 9-32. `cidr` and `inet` Functions

Function | Return Type | 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
`hostmask`(`inet`) | `inet` | construct host mask for network | hostmask('192.168.23.20/30') | 0.0.0.3
`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 netmask length as text | text(inet '192.168.1.5') | 192.168.1.5/32
`abbrev`(`inet`) | `text` | abbreviated display format as text | abbrev(cidr '10.1.0.0/16') | 10.1/16

Table 9-33 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. The directory `contrib/mac` in the source distribution contains some utilities to create and maintain such an association table.

Table 9-33. `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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