Domain Depth

This function returns the number of dot-separated levels in a domain. It extracts the host from a URL and counts the labels. Returns 0 for IP addresses, empty strings, and invalid input. Returns NULL for NULL input.

D SELECT domain_depth('example.com') AS depth;
┌───────┐
│ depth │
│ int32 │
├───────┤
│   2   │
└───────┘

D SELECT domain_depth('https://www.example.com/page') AS depth;
┌───────┐
│ depth │
│ int32 │
├───────┤
│   3   │
└───────┘

D SELECT domain_depth('http://a.b.c.example.co.uk/page') AS depth;
┌───────┐
│ depth │
│ int32 │
├───────┤
│   6   │
└───────┘

Special Cases

• IP addresses return 0 (both IPv4 and IPv6 — they are not domains)

• Single-label names like localhost return 1

• Trailing dots are stripped before counting (DNS canonical form)

D SELECT domain_depth('192.168.1.1') AS depth;
┌───────┐
│ depth │
│ int32 │
├───────┤
│   0   │
└───────┘

D SELECT domain_depth('localhost') AS depth;
┌───────┐
│ depth │
│ int32 │
├───────┤
│   1   │
└───────┘