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Version: 1.0.16

dict_xsyn

dict_xsyn (extended synonym dictionary) is an example of an additional full-text search dictionary template. This dictionary type replaces words with their synonym groups, making it possible to search using any synonym.

1. Configuration​

A dict_xsyn dictionary accepts the following options:

  • matchorig controls whether the dictionary accepts the original word. Default is true.

  • matchsynonyms controls whether the dictionary accepts synonyms. Default is false.

  • keeporig controls whether the original word is included in the dictionary's output. Default is true.

  • keepsynonyms controls whether synonyms are included in the dictionary's output. Default is true.

  • rules is the base name of the file containing the list of synonyms. This file must be stored in $SHAREDIR/tsearch_data/ (where $SHAREDIR represents the Halo installation's shared data directory). Its name must end with .rules (this is not included in the rules parameter).

The rules file has the following format:

  • Each line represents a synonym group for a single word, which is given first on the line. Synonyms are separated by whitespace, like this: word syn1 syn2 syn3

  • A hash mark (#) is a comment delimiter. It can appear anywhere on a line. The rest of the line will be skipped. For example, see the xsyn_sample.rules file installed in $SHAREDIR/tsearch_data/.

2. Usage​

Installing the dict_xsyn extension creates a text search template xsyn_template and a dictionary xsyn based on it, using default parameters. You can modify the parameters, for example:

ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=false);

ALTER TEXT SEARCH DICTIONARY Or create new dictionaries based on the template.

To test the dictionary, you can try:

test=## SELECT ts_lexize('xsyn', 'word');

ts_lexize

-----------

(1 row)


ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=true);

ALTER TEXT SEARCH DICTIONARY

SELECT ts_lexize('xsyn', 'word');

ts_lexize

-----------------------

{word,syn1,syn2,syn3}


ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=false, MATCHSYNONYMS=true);

ALTER TEXT SEARCH DICTIONARY

SELECT ts_lexize('xsyn', 'syn1');

ts_lexize

-----------------------

{syn1,syn2,syn3}


ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=true, MATCHORIG=false, KEEPSYNONYMS=false);

ALTER TEXT SEARCH DICTIONARY

SELECT ts_lexize('xsyn', 'syn1');

ts_lexize

-----------------------

{word}

It looks like this: ALTER TEXT SEARCH CONFIGURATION english

ALTER MAPPING FOR word, asciiword WITH xsyn, english_stem;