Text Search Configuration Example

Text search configuration specifies the following components required for converting a document into a tsvector:

A parser, decomposes a text into tokens.
Dictionary list, converts each token into a lexeme.

Each time when the to_tsvector or to_tsquery function is invoked, a text search configuration is required to specify a processing procedure. The GUC parameter default_text_search_config specifies the default text search configuration, which will be used if the text search function does not explicitly specify a text search configuration.

GaussDB(DWS) provides some predefined text search configurations. You can also create user-defined text search configurations. In addition, to facilitate the management of text search objects, multiple gsql meta-commands are provided to display related information. For details, see "Meta-Command Reference" in the Tool Guide.

Procedure

Create a text search configuration ts_conf by copying the predefined text search configuration english.

1 2	CREATE TEXT SEARCH CONFIGURATION ts_conf ( COPY = pg_catalog.english ); CREATE TEXT SEARCH CONFIGURATION

Create a Synonym dictionary.

Assume that the definition file pg_dict.syn of the Synonym dictionary contains the following contents:

1
2
3

postgres    pg 
pgsql       pg 
postgresql  pg

Run the following statement to create the Synonym dictionary:

CREATE TEXT SEARCH DICTIONARY pg_dict (
     TEMPLATE = synonym,
     SYNONYMS = pg_dict,
     FILEPATH =  'obs://bucket01/obs.xxx.xxx.com accesskey=xxxxx secretkey=xxxxx region=ap-southeast-1'
 );

Create an Ispell dictionary english_ispell (the dictionary definition file is from the open source dictionary).

CREATE TEXT SEARCH DICTIONARY english_ispell (
    TEMPLATE = ispell,
    DictFile = english,
    AffFile = english,
    StopWords = english,
    FILEPATH =   'obs://bucket01/obs.xxx.xxx.com accesskey=xxxxx secretkey=xxxxx region=ap-southeast-1'
);

Modify the text search configuration ts_conf and change the dictionary list for tokens of certain types. For details about token types, see Text Search Parser.

ALTER TEXT SEARCH CONFIGURATION ts_conf
    ALTER MAPPING FOR asciiword, asciihword, hword_asciipart,
                      word, hword, hword_part
    WITH pg_dict, english_ispell, english_stem;

In the text search configuration, set non-index or set the search for tokens of certain types.

1 2	ALTER TEXT SEARCH CONFIGURATION ts_conf DROP MAPPING FOR email, url, url_path, sfloat, float;

Use the text retrieval commissioning function ts_debug() to test the text search configuration ts_conf.

SELECT * FROM ts_debug('ts_conf', '
PostgreSQL, the highly scalable, SQL compliant, open source object-relational
database management system, is now undergoing beta testing of the next
version of our software.
');

You can set the default text search configuration of the current session to ts_conf. This setting is valid only for the current session.

\dF+ ts_conf
      Text search configuration "public.ts_conf"
Parser: "pg_catalog.default"
      Token      |            Dictionaries             
-----------------+-------------------------------------
 asciihword      | pg_dict,english_ispell,english_stem
 asciiword       | pg_dict,english_ispell,english_stem
 file            | simple
 host            | simple
 hword           | pg_dict,english_ispell,english_stem
 hword_asciipart | pg_dict,english_ispell,english_stem
 hword_numpart   | simple
 hword_part      | pg_dict,english_ispell,english_stem
 int             | simple
 numhword        | simple
 numword         | simple
 uint            | simple
 version         | simple
 word            | pg_dict,english_ispell,english_stem

SET default_text_search_config = 'public.ts_conf';
SET
SHOW default_text_search_config;
 default_text_search_config 
----------------------------
 public.ts_conf
(1 row)