示例

• Synonym词典可用于解决语言学相关问题，例如，为避免使单词"Paris"变成"pari"，可在Synonym词典文件中定义一行"Paris paris"，并将该词典放置在预定义的english_stem词典之前。

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  openGauss=# SELECT * FROM ts_debug('english', 'Paris'); alias | description | token | dictionaries | dictionary | lexemes -----------+-----------------+-------+----------------+--------------+--------- asciiword | Word, all ASCII | Paris | {english_stem} | english_stem | {pari}(1 row)openGauss=# CREATE TEXT SEARCH DICTIONARY my_synonym ( TEMPLATE = synonym, SYNONYMS = my_synonyms, FILEPATH = 'file:///home/dicts/' );openGauss=# ALTER TEXT SEARCH CONFIGURATION english ALTER MAPPING FOR asciiword WITH my_synonym, english_stem;openGauss=# SELECT * FROM ts_debug('english', 'Paris'); alias | description | token | dictionaries | dictionary | lexemes -----------+-----------------+-------+---------------------------+------------+--------- asciiword | Word, all ASCII | Paris | {my_synonym,english_stem} | my_synonym | {paris}(1 row)openGauss=# SELECT * FROM ts_debug('english', 'paris'); alias | description | token | dictionaries | dictionary | lexemes -----------+-----------------+-------+---------------------------+------------+--------- asciiword | Word, all ASCII | Paris | {my_synonym,english_stem} | my_synonym | {paris}(1 row)openGauss=# ALTER TEXT SEARCH DICTIONARY my_synonym ( CASESENSITIVE=true);openGauss=# SELECT * FROM ts_debug('english', 'Paris'); alias | description | token | dictionaries | dictionary | lexemes -----------+-----------------+-------+---------------------------+------------+--------- asciiword | Word, all ASCII | Paris | {my_synonym,english_stem} | my_synonym | {paris}(1 row)openGauss=# SELECT * FROM ts_debug('english', 'paris'); alias | description | token | dictionaries | dictionary | lexemes -----------+-----------------+-------+---------------------------+------------+--------- asciiword | Word, all ASCII | Paris | {my_synonym,english_stem} | my_synonym | {pari}(1 row)

  其中，同义词词典文件全名为my_synonyms.syn，所在目录为当前连接CN节点的/home/dicts/下。关于创建词典的语法和更多参数，请参见CREATE TEXT SEARCH DICTIONARY。

• 星号（*）可用于词典文件中的同义词结尾，表示该同义词是一个前缀。在to_tsvector()中该星号将被忽略，但在to_tsquery()中会匹配该前缀并对应输出结果（参照处理查询一节）。

  假设词典文件synonym_sample.syn内容如下：

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  postgres pgsqlpostgresql pgsql postgre pgsql gogle googl indices index*

  创建并使用词典：

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  openGauss=# CREATE TEXT SEARCH DICTIONARY syn ( TEMPLATE = synonym, SYNONYMS = synonym_sample);openGauss=# SELECT ts_lexize('syn','indices'); ts_lexize ----------- {index}(1 row)openGauss=# CREATE TEXT SEARCH CONFIGURATION tst (copy=simple);openGauss=# ALTER TEXT SEARCH CONFIGURATION tst ALTER MAPPING FOR asciiword WITH syn;openGauss=# SELECT to_tsvector('tst','indices'); to_tsvector ------------- 'index':1(1 row)openGauss=# SELECT to_tsquery('tst','indices'); to_tsquery ------------ 'index':*(1 row)openGauss=# SELECT 'indexes are very useful'::tsvector; tsvector --------------------------------- 'are' 'indexes' 'useful' 'very'(1 row)openGauss=# SELECT 'indexes are very useful'::tsvector @@ to_tsquery('tst','indices'); ?column? ---------- t(1 row)