url_* session settings

These settings are available in system.settings and are autogenerated from source.

url_base

The base URL used to resolve relative URLs in the url table function and the URL table engine. When set, relative URLs are resolved as follows:

Path-relative URL (e.g. data.csv): merged with the base URL path per RFC 3986. Everything after the last / in the base path is replaced by the relative URL, so a trailing slash matters: https://example.com/dir/ + data.csv = https://example.com/dir/data.csv, but https://example.com/dir + data.csv = https://example.com/data.csv. If the base has no path (e.g. https://example.com), a / is inserted: https://example.com/data.csv. Dot segments (./ and ../) in the relative URL are normalized: https://example.com/dir/ + ../a.csv = https://example.com/a.csv.
Host-relative URL (e.g. /test/data.csv): resolved against the base URL’s scheme and host.
Scheme-relative URL (e.g. //other.com/test/data.csv): resolved using the base URL’s scheme.
Query-only reference (e.g. ?x=1): appended to the base URL path (replacing any existing query/fragment).
Fragment-only reference (e.g. #frag): appended to the base URL, preserving any query string (replacing any existing fragment).
Empty reference: returns the base URL without fragment.
If the base URL is only a scheme (e.g. file://), a path-relative URL is appended to it directly: file:// + data.csv = file://data.csv, which for the file:// scheme means a path relative to the user_files directory (the current directory for clickhouse-local). Dot segments are kept as-is in this case, so the target engine resolves them against its own base directory.

For example, if url_base is https://example.com/def/, then:

Maximum number of directories that can be traversed while expanding URL wildcards from index pages.