9.3 KiB
| toc_priority | toc_title |
|---|---|
| 54 | URLs |
Functions for Working with URLs
All these functions don’t follow the RFC. They are maximally simplified for improved performance.
Functions that Extract Parts of a URL
If the relevant part isn’t present in a URL, an empty string is returned.
protocol
Extracts the protocol from a URL.
Examples of typical returned values: http, https, ftp, mailto, tel, magnet…
domain
Extracts the hostname from a URL.
domain(url)
Parameters
url— URL. Type: String.
The URL can be specified with or without a scheme. Examples:
svn+ssh://some.svn-hosting.com:80/repo/trunk
some.svn-hosting.com:80/repo/trunk
https://yandex.com/time/
For these examples, the domain function returns the following results:
some.svn-hosting.com
some.svn-hosting.com
yandex.com
Returned values
- Host name. If ClickHouse can parse the input string as a URL.
- Empty string. If ClickHouse can’t parse the input string as a URL.
Type: String.
Example
SELECT domain('svn+ssh://some.svn-hosting.com:80/repo/trunk')
┌─domain('svn+ssh://some.svn-hosting.com:80/repo/trunk')─┐
│ some.svn-hosting.com │
└────────────────────────────────────────────────────────┘
domainWithoutWWW
Returns the domain and removes no more than one ‘www.’ from the beginning of it, if present.
topLevelDomain
Extracts the the top-level domain from a URL.
topLevelDomain(url)
Parameters
url— URL. Type: String.
The URL can be specified with or without a scheme. Examples:
svn+ssh://some.svn-hosting.com:80/repo/trunk
some.svn-hosting.com:80/repo/trunk
https://yandex.com/time/
Returned values
- Domain name. If ClickHouse can parse the input string as a URL.
- Empty string. If ClickHouse cannot parse the input string as a URL.
Type: String.
Example
SELECT topLevelDomain('svn+ssh://www.some.svn-hosting.com:80/repo/trunk')
┌─topLevelDomain('svn+ssh://www.some.svn-hosting.com:80/repo/trunk')─┐
│ com │
└────────────────────────────────────────────────────────────────────┘
firstSignificantSubdomain
Returns the “first significant subdomain”. This is a non-standard concept specific to Yandex.Metrica. 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.yandex.ru/’) = ‘yandex’, firstSignificantSubdomain (‘https://news.yandex.com.tr/’) = ‘yandex’. The list of “insignificant” second-level domains and other implementation details may change in the future.
cutToFirstSignificantSubdomain
Returns the part of the domain that includes top-level subdomains up to the “first significant subdomain” (see the explanation above).
For example, cutToFirstSignificantSubdomain('https://news.yandex.com.tr/') = 'yandex.com.tr'.
port(URL[, default_port = 0])
Returns the port or default_port if there is no port in the URL (or in case of validation error).
path
Returns the path. Example: /top/news.html The path does not include the query string.
pathFull
The same as above, but including query string and fragment. Example: /top/news.html?page=2#comments
queryString
Returns the query string. Example: page=1&lr=213. query-string does not include the initial question mark, as well as # and everything after #.
fragment
Returns the fragment identifier. fragment does not include the initial hash symbol.
queryStringAndFragment
Returns the query string and fragment identifier. Example: page=1#29390.
extractURLParameter(URL, name)
Returns the value of the ‘name’ parameter in the URL, if present. Otherwise, an empty string. If there are many parameters with this name, it returns the first occurrence. This function works under the assumption that the parameter name is encoded in the URL exactly the same way as in the passed argument.
extractURLParameters(URL)
Returns an array of name=value strings corresponding to the URL parameters. The values are not decoded in any way.
extractURLParameterNames(URL)
Returns an array of name strings corresponding to the names of URL parameters. The values are not decoded in any way.
URLHierarchy(URL)
Returns an array containing the URL, truncated at the end by the symbols /,? in the path and query-string. Consecutive separator characters are counted as one. The cut is made in the position after all the consecutive separator characters.
URLPathHierarchy(URL)
The same as above, but without the protocol and host in the result. The / element (root) is not included. Example: the function is used to implement tree reports the URL in Yandex. Metric.
URLPathHierarchy('https://example.com/browse/CONV-6788') =
[
'/browse/',
'/browse/CONV-6788'
]
decodeURLComponent(URL)
Returns the decoded URL. Example:
SELECT decodeURLComponent('http://127.0.0.1:8123/?query=SELECT%201%3B') AS DecodedURL;
┌─DecodedURL─────────────────────────────┐
│ http://127.0.0.1:8123/?query=SELECT 1; │
└────────────────────────────────────────┘
netloc
Extracts network locality (username:password@host:port) from a URL.
Syntax
netloc(URL)
Parameters
url— URL. String.
Returned value
username:password@host:port.
Type: String.
Example
Query:
SELECT netloc('http://paul@www.example.com:80/');
Result:
┌─netloc('http://paul@www.example.com:80/')─┐
│ paul@www.example.com:80 │
└───────────────────────────────────────────┘
Functions that Remove Part of a URL
If the URL doesn’t have anything similar, the URL remains unchanged.
cutWWW
Removes no more than one ‘www.’ from the beginning of the URL’s domain, if present.
cutQueryString
Removes query string. The question mark is also removed.
cutFragment
Removes the fragment identifier. The number sign is also removed.
cutQueryStringAndFragment
Removes the query string and fragment identifier. The question mark and number sign are also removed.
cutURLParameter(URL, name)
Removes the ‘name’ URL parameter, if present. This function works under the assumption that the parameter name is encoded in the URL exactly the same way as in the passed argument.
normalizeQuery
Replaces literals, sequences of literals and complex aliases with placeholders.
Syntax (without SELECT)
<function syntax>
Alias: <alias name>. (Optional)
More text (Optional).
Parameters (Optional)
Returned value(s)
- Returned values list.
Type: Type.
Example
SELECT count() FROM table WHERE date = '2020-01-02' AND id IN (1, 2, 3) LIMIT 10, 10 should be replaced to SELECT count() FROM table WHERE date = ? AND id IN (?) LIMIT ?
Query:
Result:
normalizedQueryHash
Returns identical 64bit hash values for similar queries. It helps to analyze query log. calculate a hash of query structure without the values of literals.
Syntax (without SELECT)
<function syntax>
Alias: <alias name>. (Optional)
More text (Optional).
Parameters (Optional)
Returned value(s)
- Returned values list.
Type: Type.
Example
The example must show usage and/or a use cases. The following text contains recommended parts of an example.
Input table (Optional):
Query:
Result: