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Overview

The functions mentioned in this section are optimized for maximum performance and for the most part do not follow the RFC-3986 standard. Functions which implement RFC-3986 have RFC appended to their function name and are generally slower.
You can generally use the non-RFC function variants when working with publicly registered domains that contain neither user strings nor @ symbols. The table below details which symbols in a URL can () or cannot () be parsed by the respective RFC and non-RFC variants: symbols marked * are sub-delimiters in RFC 3986 and allowed for user info following the @ symbol. There are two types of URL functions:
  • Functions that extract parts of a URL. If the relevant part isn’t present in a URL, an empty string is returned.
  • Functions that remove part of a URL. If the URL does not have anything similar, the URL remains unchanged.
The functions below are generated from the system.functions system table.

URLHierarchy

Introduced in: v1.1.0 Returns an array containing the URL, truncated at the end by the symbols /, ? and # in the path and query string. Consecutive separator characters are counted as one. The result includes the protocol and host as the first element, with progressively longer paths forming a hierarchy. Syntax
Arguments
  • url — The URL to process. String
Returned value Returns an array of progressively longer URLs forming a hierarchy. Array(String) Examples Basic usage
Query
Response

URLPathHierarchy

Introduced in: v1.1.0 Returns an array containing the path component of the URL, truncated at the end by the symbols /, ? and #. Unlike URLHierarchy, the result does not include the protocol and host — it starts from the path. Consecutive separator characters are counted as one. Syntax
Arguments
  • url — The URL to process. String
Returned value Returns an array of progressively longer URL path components forming a hierarchy. Array(String) Examples Basic usage
Query
Response

cutFragment

Introduced in: v1.1.0 Removes the fragment identifier, including the number sign, from a URL. Syntax
Arguments Returned value Returns the URL with fragment identifier removed. String Examples Usage example
Query
Response

cutQueryString

Introduced in: v1.1.0 Removes the query string, including the question mark from a URL. Syntax
Arguments Returned value Returns the URL with query string removed. String Examples Usage example
Query
Response

cutQueryStringAndFragment

Introduced in: v1.1.0 Removes the query string and fragment identifier, including the question mark and number sign, from a URL. Syntax
Arguments Returned value Returns the URL with query string and fragment identifier removed. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomain

Introduced in: v1.1.0 Returns the part of the domain that includes top-level subdomains up to the first significant subdomain. Syntax
Arguments
  • url — URL or domain string to process. String
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain if possible, otherwise returns an empty string. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomainCustom

Introduced in: v21.1.0 Returns the part of the domain that includes top-level subdomains up to the first significant subdomain. Accepts custom TLD list name. This function can be useful if you need a fresh TLD list or if you have a custom list. Configuration example
Syntax
Arguments
  • url — URL or domain string to process. String
  • tld_list_name — Name of the custom TLD list configured in ClickHouse. const String
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain. String Examples Using custom TLD list for non-standard domains
Query
Response

cutToFirstSignificantSubdomainCustomRFC

Introduced in: v22.10.0 Returns the part of the domain that includes top-level subdomains up to the first significant subdomain. Accepts custom TLD list name. This function can be useful if you need a fresh TLD list or if you have a custom list. Similar to cutToFirstSignificantSubdomainCustom but conforms to RFC 3986. Configuration example
Syntax
Arguments
  • url — URL or domain string to process according to RFC 3986. - tld_list_name — Name of the custom TLD list configured in ClickHouse.
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomainCustomWithWWW

Introduced in: v21.1.0 Returns the part of the domain that includes top-level subdomains up to the first significant subdomain without stripping ‘www’. Accepts custom TLD list name. It can be useful if you need a fresh TLD list or if you have a custom list. Configuration example
Arguments
  • url — URL or domain string to process. - tld_list_name — Name of the custom TLD list configured in ClickHouse.
Returned value Part of the domain that includes top-level subdomains up to the first significant subdomain without stripping ‘www’. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomainCustomWithWWWRFC

Introduced in: v22.10.0 Returns the part of the domain that includes top-level subdomains up to the first significant subdomain without stripping www. Accepts custom TLD list name. It can be useful if you need a fresh TLD list or if you have a custom list. Similar to cutToFirstSignificantSubdomainCustomWithWWW but conforms to RFC 3986. Configuration example
Arguments
  • url — URL or domain string to process according to RFC 3986. - tld_list_name — Name of the custom TLD list configured in ClickHouse.
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain without stripping www. String Examples RFC 3986 parsing preserving www with custom TLD list
Query
Response

cutToFirstSignificantSubdomainRFC

Introduced in: v22.10.0 Returns the part of the domain that includes top-level subdomains up to the “first significant subdomain”. Similar to cutToFirstSignificantSubdomain but conforms to RFC 3986. Syntax
Arguments
  • url — URL or domain string to process according to RFC 3986. String
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain if possible, otherwise returns an empty string. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomainWithWWW

Introduced in: v20.12.0 Returns the part of the domain that includes top-level subdomains up to the “first significant subdomain”, without stripping ‘www.’. Similar to cutToFirstSignificantSubdomain but preserves the ‘www.’ prefix if present. Syntax
Arguments
  • url — URL or domain string to process. String
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain (with www) if possible, otherwise returns an empty string. String Examples Usage example
Query
Response

cutToFirstSignificantSubdomainWithWWWRFC

Introduced in: v22.10.0 Returns the part of the domain that includes top-level subdomains up to the “first significant subdomain”, without stripping ‘www’. Similar to cutToFirstSignificantSubdomainWithWWW but conforms to RFC 3986. Syntax
Arguments
  • url — URL or domain string to process according to RFC 3986.
Returned value Returns the part of the domain that includes top-level subdomains up to the first significant subdomain (with ‘www’) if possible, otherwise returns an empty string String Examples Usage example
Query
Response

cutURLParameter

Introduced in: v1.1.0 Removes the name parameter from a URL, if present. This function does not encode or decode characters in parameter names, e.g. Client ID and Client%20ID are treated as different parameter names. Syntax
Arguments Returned value URL with name URL parameter removed. String Examples Usage example
Query
Response

cutWWW

Introduced in: v1.1.0 Removes the leading www., if present, from the URL’s domain. Syntax
Arguments Returned value Returns the URL with leading www. removed from the domain. String Examples Usage example
Query
Response

decodeURLComponent

Introduced in: v1.1.0 Takes a URL-encoded string as input and decodes it back to its original, readable form. Syntax
Arguments Returned value Returns the decoded URL. String Examples Usage example
Query
Response

decodeURLFormComponent

Introduced in: v1.1.0 Decodes URL-encoded strings using form encoding rules (RFC-1866), where + signs are converted to spaces and percent-encoded characters are decoded. Syntax
Arguments Returned value Returns the decoded URL. String Examples Usage example
Query
Response

domain

Introduced in: v1.1.0 Extracts the hostname from a URL. The URL can be specified with or without a protocol. Syntax
Arguments Returned value Returns the host name if the input string can be parsed as a URL, otherwise an empty string. String Examples Usage example
Query
Response

domainRFC

Introduced in: v22.10.0 Extracts the hostname from a URL. Similar to domain, but RFC 3986 conformant. Syntax
Arguments Returned value Returns the host name if the input string can be parsed as a URL, otherwise an empty string. String Examples Usage example
Query
Response

domainWithoutWWW

Introduced in: v1.1.0 Returns the domain of a URL without leading www. if present. Syntax
Arguments Returned value Returns the domain name if the input string can be parsed as a URL (without leading www.), otherwise an empty string. String Examples Usage example
Query
Response

domainWithoutWWWRFC

Introduced in: v1.1.0 Returns the domain without leading www. if present. Similar to domainWithoutWWW but conforms to RFC 3986. Syntax
Arguments Returned value Returns the domain name if the input string can be parsed as a URL (without leading www.), otherwise an empty string. String Examples Usage example
Query
Response

encodeURLComponent

Introduced in: v22.3.0 Takes a regular string and converts it into a URL-encoded (percent-encoded) format where special characters are replaced with their percent-encoded equivalents. Syntax
Arguments Returned value Returns the encoded URL. String Examples Usage example
Query
Response

encodeURLFormComponent

Introduced in: v22.3.0 Encodes strings using form encoding rules (RFC-1866), where spaces are converted to + signs and special characters are percent-encoded. Syntax
Arguments Returned value Returns the encoded URL. String Examples Usage example
Query
Response

extractURLParameter

Introduced in: v1.1.0 Returns the value of the name parameter in the URL, if present, otherwise an empty string is returned. If there are multiple parameters with this name, the first occurrence is returned. The function assumes that the parameter in the url parameter is encoded in the same way as in the name argument. Syntax
Arguments Returned value Returns the value of the URL parameter with the specified name. String Examples Usage example
Query
Response

extractURLParameterNames

Introduced in: v1.1.0 Returns an array of name strings corresponding to the names of URL parameters. The values are not decoded. Syntax
Arguments Returned value Returns an array of name strings corresponding to the names of URL parameters. Array(String) Examples Usage example
Query
Response

extractURLParameters

Introduced in: v1.1.0 Returns an array of name=value strings corresponding to the URL parameters. The values are not decoded. Syntax
Arguments Returned value Returns an array of name=value strings corresponding to the URL parameters. Array(String) Examples Usage example
Query
Response

firstSignificantSubdomain

Introduced in: v1.1.0 Returns the “first significant subdomain”. The first significant subdomain is a second-level domain if it is ‘com’, ‘net’, ‘org’, or ‘co’. Otherwise, it is a third-level domain. For example, firstSignificantSubdomain(‘https://news.clickhouse.com/’) = ‘clickhouse’, firstSignificantSubdomain (‘https://news.clickhouse.com.tr/’) = ‘clickhouse’. The list of “insignificant” second-level domains and other implementation details may change in the future. Syntax
Arguments
  • None.
Returned value Examples firstSignificantSubdomain
Query
Response

firstSignificantSubdomainCustom

Introduced in: v21.1.0 Returns the first significant subdomain of a URL using a custom TLD (Top-Level Domain) list. The custom TLD list name refers to a configuration that defines which domain suffixes should be treated as top-level domains. This is useful for non-standard TLD hierarchies. The function uses a simplified URL parsing algorithm that assumes the protocol and everything following are stripped. Syntax
Arguments
  • url — The URL to extract the subdomain from. String
  • tld_list_name — Name of the custom TLD list from the configuration. String
Returned value Returns the first significant subdomain. String Examples Basic usage
Query
Response

firstSignificantSubdomainCustomRFC

Introduced in: v22.10.0 Similar to firstSignificantSubdomainCustom but uses RFC 3986 compliant URL parsing instead of the simplified algorithm. Syntax
Arguments
  • url — The URL to extract the subdomain from. String
  • tld_list_name — Name of the custom TLD list from the configuration. String
Returned value Returns the first significant subdomain. String Examples Basic usage
Query
Response

firstSignificantSubdomainRFC

Introduced in: v22.10.0 Returns the “first significant subdomain” according to RFC 1034. Syntax
Arguments
  • None.
Returned value Examples

fragment

Introduced in: v1.1.0 Returns the fragment identifier without the initial hash symbol. Syntax
Arguments Returned value Returns the fragment identifier without the initial hash symbol. String Examples Usage example
Query
Response

netloc

Introduced in: v20.5.0 Extracts network locality (username:password@host:port) from a URL. Syntax
Arguments Returned value Returns username:password@host:port from a given URL. String Examples Usage example
Query
Response

path

Introduced in: v1.1.0 Returns the path without query string from a URL. Syntax
Arguments Returned value Returns the path of the URL without query string. String Examples Usage example
Query
Response

pathFull

Introduced in: v1.1.0 The same as path, but includes the query string and fragment of the URL. Syntax
Arguments Returned value Returns the path of the URL including query string and fragment. String Examples Usage example
Query
Response

port

Introduced in: v20.5.0 Returns the port of a URL, or the default_port if the URL contains no port or cannot be parsed. Syntax
Arguments
  • url — URL. String
  • default_port — Optional. The default port number to be returned. 0 by default. UInt16
Returned value Returns the port of the URL, or the default port if there is no port in the URL or in case of a validation error. UInt16 Examples Usage example
Query
Response

portRFC

Introduced in: v22.10.0 Returns the port or default_port if the URL contains no port or cannot be parsed. Similar to port, but RFC 3986 conformant. Syntax
Arguments
  • url — URL. String
  • default_port — Optional. The default port number to be returned. 0 by default. UInt16
Returned value Returns the port or the default port if there is no port in the URL or in case of a validation error. UInt16 Examples Usage example
Query
Response

protocol

Introduced in: v1.1.0 Extracts the protocol from a URL. Examples of typical returned values: http, https, ftp, mailto, tel, magnet. Syntax
Arguments Returned value Returns the protocol of the URL, or an empty string if it cannot be determined. String Examples Usage example
Query
Response

queryString

Introduced in: v1.1.0 Returns the query string of a URL without the initial question mark, # and everything after #. Syntax
Arguments Returned value Returns the query string of the URL without the initial question mark and fragment. String Examples Usage example
Query
Response

queryStringAndFragment

Introduced in: v1.1.0 Returns the query string and fragment identifier of a URL. Syntax
Arguments Returned value Returns the query string and fragment identifier of the URL. String Examples Usage example
Query
Response

topLevelDomain

Introduced in: v1.1.0 Extracts the the top-level domain from a URL.
The URL can be specified with or without a protocol. For example:
Syntax
Arguments Returned value Returns the domain name if the input string can be parsed as a URL. Otherwise, an empty string. String Examples Usage example
Query
Response

topLevelDomainRFC

Introduced in: v22.10.0 Extracts the the top-level domain from a URL. Similar to topLevelDomain, but conforms to RFC 3986. Syntax
Arguments Returned value Domain name if the input string can be parsed as a URL. Otherwise, an empty string. String Examples Usage example
Query
Response
Last modified on June 23, 2026