F.52. pg_tsparser

pg_tsparser is a Postgres Pro extension for text search. This extension modifies the default text parsing strategy for words that include:

  • underscores

  • numbers and letters separated by the hyphen character

In addition to separate word parts returned by default, pg_tsparser also returns the whole word.

F.52.1. Installation and Setup

pg_tsparser is included into the Postgres Pro distribution. To enable pg_tsparser, once Postgres Pro is installed, create the pg_tsparser extension for each database you are planning to use:

CREATE EXTENSION pg_tsparser;

Once pg_tsparser is enabled, you can create your own text search configuration. In addition to pg_tsparser, you can use any available dictionary.

For example, you can create english_ts configuration for the English language, as follows:

CREATE TEXT SEARCH CONFIGURATION english_ts (
    PARSER = tsparser
);

COMMENT ON TEXT SEARCH CONFIGURATION english_ts IS 'text search configuration for english language';

ALTER TEXT SEARCH CONFIGURATION english_ts
    ADD MAPPING FOR email, file, float, host, hword_numpart, int,
    numhword, numword, sfloat, uint, url, url_path, version
    WITH simple;

ALTER TEXT SEARCH CONFIGURATION english_ts
    ADD MAPPING FOR asciiword, asciihword, hword_asciipart,
    word, hword, hword_part
    WITH english_stem;

F.52.2. Examples

The following examples illustrate the difference in search results returned by pg_tsparser and the default parser:

SELECT to_tsvector('english', 'pg_trgm') as def_parser,
       to_tsvector('english_ts', 'pg_trgm')  as new_parser;
   def_parser    |         new_parser
-----------------+-----------------------------
 'pg':1 'trgm':2 | 'pg':2 'pg_trgm':1 'trgm':3
(1 row)

SELECT to_tsvector('english', '123-abc') as def_parser,
       to_tsvector('english_ts', '123-abc')  as new_parser;
   def_parser    |         new_parser
-----------------+-----------------------------
 '123':1 'abc':2 | '123':2 '123-abc':1 'abc':3
(1 row)

SELECT to_tsvector('english', 'rel-3.2-A') as def_parser,
       to_tsvector('english_ts', 'rel-3.2-A')  as new_parser;
    def_parser    |          new_parser
------------------+-------------------------------
 '-3.2':2 'rel':1 | '3.2':3 'rel':2 'rel-3.2-a':1
(1 row)

See Also

CREATE TEXT SEARCH CONFIGURATION

ALTER TEXT SEARCH CONFIGURATION

F.52.3. Authors

Postgres Professional, Moscow, Russia