path_hierarchy

The path_hierarchy template tokenizes a hierarchical path into every prefix along the way, so a value indexed at /usr/local/bin is also found by a search for /usr or /usr/local.

This is ideal for file paths, category trees and URL paths where you want a query on any ancestor to match the descendants stored beneath it. By default it splits on /; set DELIMITER to use another separator. With REVERSE = true it builds the hierarchy from the right instead — the natural choice for domain names, where docs.serenedb.com should also match serenedb.com and com. Unlike a plain delimiter split, which would emit the individual components, path_hierarchy emits the cumulative prefixes.

Options

Option	Type	Default	Description
DELIMITER	string	'/'	Path separator character or string
REPLACEMENT	string	same as DELIMITER	String that replaces the delimiter in the emitted tokens
REVERSE	boolean	false	Build the hierarchy from the right (for domain-like values)
SKIP	integer	0	Number of leading components to drop before building prefixes
BUFFERSIZE	integer	1024	Term buffer size hint (characters per pass)

Tokenization

Each token is a cumulative prefix of the path. The input is cut on DELIMITER and one token is emitted for the first component, then for the first two, and so on up to the whole value. REVERSE builds the prefixes from the trailing end instead; SKIP discards a number of leading components before prefixes are formed; REPLACEMENT rewrites the delimiter character in the output.

The table shows the tokens emitted for a few option combinations:

Options	Input	Tokens
DELIMITER = '/'	/usr/local/bin	/usr, /usr/local, /usr/local/bin
DELIMITER = '/', SKIP = 1	/usr/local/bin	/local, /local/bin
DELIMITER = '.', REVERSE = true	docs.serenedb.com	docs.serenedb.com, serenedb.com, com

Index a filesystem path into its ancestors

A search for any ancestor prefix matches every path stored beneath it:

Query

CREATE TEXT SEARCH DICTIONARY path_dict (    template = 'path_hierarchy',    delimiter = '/');
SELECT ts_lexize('path_dict', '/usr/local/bin');

Result

 ts_lexize---------------------------------- {/usr,/usr/local,/usr/local/bin}

Reverse mode for a domain name

With REVERSE = true and DELIMITER = '.' the prefixes grow from the right, so a subdomain matches its parent domains:

Query

CREATE TEXT SEARCH DICTIONARY domain_dict (    template = 'path_hierarchy',    delimiter = '.',    reverse = true);
SELECT ts_lexize('domain_dict', 'docs.serenedb.com');

Result

 ts_lexize-------------------------------------- {docs.serenedb.com,serenedb.com,com}

Skip leading components

SKIP = 1 drops the first component before building the prefixes — useful for stripping a common root such as a mount point or a leading category:

Query

CREATE TEXT SEARCH DICTIONARY path_skip (    template = 'path_hierarchy',    delimiter = '/',    skip = 1);
SELECT ts_lexize('path_skip', '/usr/local/bin');

Result

 ts_lexize--------------------- {/local,/local/bin}

See also

• delimiter — split on a single delimiter without building prefixes
• CREATE TEXT SEARCH DICTIONARY