Configuration Examples

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.

openGauss 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 information about text search objects. For details, see “Client Tool > Meta-Command Reference” in Tool Reference.

Procedure

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

    openGauss=# CREATE TEXT SEARCH CONFIGURATION ts_conf ( COPY = pg_catalog.english );
    CREATE TEXT SEARCH CONFIGURATION
    
  2. Create a Synonym dictionary.

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

    postgres    pg 
    pgsql       pg 
    postgresql  pg
    

    Run the following statement to create the Synonym dictionary:

    openGauss=# CREATE TEXT SEARCH DICTIONARY pg_dict (
         TEMPLATE = synonym,
         SYNONYMS = pg_dict,
         FILEPATH = 'file:///home/dicts'
     );
    
  3. Create an Ispell dictionary english_ispell (the dictionary definition file is from the open source dictionary).

    openGauss=# CREATE TEXT SEARCH DICTIONARY english_ispell (
        TEMPLATE = ispell,
        DictFile = english,
        AffFile = english,
        StopWords = english,
        FILEPATH = 'file:///home/dicts' 
    );
    
  4. Modify the text search configuration ts_conf and change the dictionary list for tokens of certain types. For details about token types, see Parser.

    openGauss=# ALTER TEXT SEARCH CONFIGURATION ts_conf
        ALTER MAPPING FOR asciiword, asciihword, hword_asciipart,
                          word, hword, hword_part
        WITH pg_dict, english_ispell, english_stem;
    
  5. In the text search configuration, set non-index or set the search for tokens of certain types.

    openGauss=# ALTER TEXT SEARCH CONFIGURATION ts_conf
        DROP MAPPING FOR email, url, url_path, sfloat, float;
    
  6. Use the text retrieval commissioning function ts_debug() to test the text search configuration ts_conf.

    openGauss=# 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.
    ');
    
  7. You can set the default text search configuration of the current session to ts_conf. This setting is valid only for the current session.

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