文本检索函数和操作符

文本检索操作符

• @@

  描述: tsvector类型的词汇与tsquery类型的词汇是否匹配

  示例:

  MogDB=# SELECT to_tsvector('fat cats ate rats') @@ to_tsquery('cat & rat') AS RESULT;
   result
  --------
   t
  (1 row)

• @@@

  描述: @@的同义词

  示例:

  MogDB=# SELECT to_tsvector('fat cats ate rats') @@@ to_tsquery('cat & rat') AS RESULT;
   result
  --------
   t
  (1 row)

• ||

  描述: 连接两个tsvector类型的词汇

  示例:

  MogDB=# SELECT 'a:1 b:2'::tsvector || 'c:1 d:2 b:3'::tsvector AS RESULT;
            result
  ---------------------------
   'a':1 'b':2,5 'c':3 'd':4
  (1 row)

• &&

  描述: 将两个tsquery类型的词汇进行"与"操作

  示例:

  MogDB=# SELECT 'fat | rat'::tsquery && 'cat'::tsquery AS RESULT;
            result
  ---------------------------
   'fat' | 'rat' | 'cat'
  (1 row)

• ||

  描述: 将两个tsquery类型的词汇进行"或"操作

  示例:

  MogDB=# SELECT 'fat | rat'::tsquery || 'cat'::tsquery AS RESULT;
            result
  ---------------------------
   ( 'fat' | 'rat' ) | 'cat'
  (1 row)

• !!

  描述: tsquery类型词汇的非关系

  示例:

  MogDB=# SELECT !! 'cat'::tsquery AS RESULT;
   result
  --------
   !'cat'
  (1 row)

• @>

  描述: 一个tsquery类型的词汇是否包含另一个tsquery类型的词汇

  示例:

  MogDB=# SELECT 'cat'::tsquery @> 'cat & rat'::tsquery AS RESULT;
   result
  --------
   f
  (1 row)

• <@

  描述: 一个tsquery类型的词汇是否被包含另一个tsquery类型的词汇

  示例:

  MogDB=# SELECT 'cat'::tsquery <@ 'cat & rat'::tsquery AS RESULT;
   result
  --------
   t
  (1 row)

除了上述的操作符，还为tsvector类型和tsquery类型的数据定义了普通的B-tree比较操作符（=、<等）。

文本检索函数

• get_current_ts_config()

  描述: 获取文本检索的默认配置。

  返回类型: regconfig

  示例:

  MogDB=# SELECT get_current_ts_config();
   get_current_ts_config
  -----------------------
   english
  (1 row)

• length(tsvector)

  描述: tsvector类型词汇的单词数。

  返回类型: integer

  示例:

  MogDB=# SELECT length('fat:2,4 cat:3 rat:5A'::tsvector);
   length
  --------
        3
  (1 row)

• numnode(tsquery)

  描述: tsquery类型的单词加上操作符的数量。

  返回类型: integer

  示例:

  MogDB=# SELECT numnode('(fat & rat) | cat'::tsquery);
   numnode
  ---------
         5
  (1 row)

• plainto_tsquery([ config regconfig , ] query text)

  描述: 产生tsquery类型的词汇，并忽略标点。

  返回类型: tsquery

  示例:

  MogDB=# SELECT plainto_tsquery('english', 'The Fat Rats');
   plainto_tsquery
  -----------------
   'fat' & 'rat'
  (1 row)

• querytree(query tsquery)

  描述: 获取tsquery类型的词汇可加索引的部分。

  返回类型: text

  示例:

  MogDB=# SELECT querytree('foo & ! bar'::tsquery);
   querytree
  -----------
   'foo'
  (1 row)

• setweight(tsvector, "char")

  描述: 给tsvector类型的每个元素分配权值。

  返回类型: tsvector

  示例:

  MogDB=# SELECT setweight('fat:2,4 cat:3 rat:5B'::tsvector, 'A');
             setweight
  -------------------------------
   'cat':3A 'fat':2A,4A 'rat':5A
  (1 row)

• strip(tsvector)

  描述: 删除tsvector类型单词中的position和权值。

  返回类型: tsvector

  示例:

  MogDB=# SELECT strip('fat:2,4 cat:3 rat:5A'::tsvector);
         strip
  -------------------
   'cat' 'fat' 'rat'
  (1 row)

• to_tsquery([ config regconfig , ] query text)

  描述: 标准化单词，并转换为tsquery类型。

  返回类型: tsquery

  示例:

  MogDB=# SELECT to_tsquery('english', 'The & Fat & Rats');
    to_tsquery
  ---------------
   'fat' & 'rat'
  (1 row)

• to_tsvector([ config regconfig , ] document text)

  描述: 去除文件信息，并转换为tsvector类型。

  返回类型: tsvector

  示例:

  MogDB=# SELECT to_tsvector('english', 'The Fat Rats');
     to_tsvector
  -----------------
   'fat':2 'rat':3
  (1 row)

• to_tsvector_for_batch([ config regconfig , ] document text)

  描述：去除文件信息，并转换为tsvector类型。

  返回类型：tsvector

  示例：

  MogDB=# SELECT to_tsvector_for_batch('english', 'The Fat Rats');
     to_tsvector
  -----------------
   'fat':2 'rat':3
  (1 row)

• ts_headline([ config regconfig, ] document text, query tsquery [, options text ])

  描述: 高亮显示查询的匹配项。

  返回类型: text

  示例:

  MogDB=# SELECT ts_headline('x y z', 'z'::tsquery);
   ts_headline
  --------------
   x y <b>z</b>
  (1 row)

• ts_rank([ weights float4[], ] vector tsvector, query tsquery [, normalization integer ])

  描述: 文档查询排名。

  返回类型: float4

  示例:

  MogDB=# SELECT ts_rank('hello world'::tsvector, 'world'::tsquery);
   ts_rank
  ----------
   .0607927
  (1 row)

• ts_rank_cd([ weights float4[], ] vector tsvector, query tsquery [, normalization integer ])

  描述: 排序文件查询使用覆盖密度。

  返回类型: float4

  示例:

  MogDB=# SELECT ts_rank_cd('hello world'::tsvector, 'world'::tsquery);
   ts_rank_cd
  ------------
            .1
  (1 row)

• ts_rewrite(query tsquery, target tsquery, substitute tsquery)

  描述: 替换目标tsquery类型的单词。

  返回类型: tsquery

  示例:

  MogDB=# SELECT ts_rewrite('a & b'::tsquery, 'a'::tsquery, 'foo|bar'::tsquery);
         ts_rewrite
  -------------------------
   'b' & ( 'foo' | 'bar' )
  (1 row)

• ts_rewrite(query tsquery, select text)

  描述: 使用SELECT命令的结果替代目标中tsquery类型的单词。

  返回类型: tsquery

  示例:

  MogDB=# SELECT ts_rewrite('world'::tsquery, 'select ''world''::tsquery, ''hello''::tsquery');
   ts_rewrite
  ------------
   'hello'
  (1 row)

文本检索调试函数

• ts_debug([ config regconfig, ] document text, OUT alias text, OUT description text, OUT token text, OUT dictionaries regdictionary[], OUT dictionary regdictionary, OUT lexemes text[])

  描述: 测试一个配置。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_debug('english', 'The Brightest supernovaes');
                                       ts_debug
  -----------------------------------------------------------------------------------
   (asciiword,"Word, all ASCII",The,{english_stem},english_stem,{})
   (blank,"Space symbols"," ",{},,)
   (asciiword,"Word, all ASCII",Brightest,{english_stem},english_stem,{brightest})
   (blank,"Space symbols"," ",{},,)
   (asciiword,"Word, all ASCII",supernovaes,{english_stem},english_stem,{supernova})
  (5 rows)

• ts_lexize(dict regdictionary, token text)

  描述: 测试一个数据字典。

  返回类型: text[]

  示例:

  MogDB=# SELECT ts_lexize('english_stem', 'stars');
   ts_lexize
  -----------
   {star}
  (1 row)

• ts_parse(parser_name text, document text, OUT tokid integer, OUT token text)

  描述: 测试一个解析。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_parse('default', 'foo - bar');
   ts_parse
  -----------
   (1,foo)
   (12," ")
   (12,"- ")
   (1,bar)
  (4 rows)

• ts_parse(parser_oid oid, document text, OUT tokid integer, OUT token text)

  描述: 测试一个解析。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_parse(3722, 'foo - bar');
   ts_parse
  -----------
   (1,foo)
   (12," ")
   (12,"- ")
   (1,bar)
  (4 rows)

• ts_token_type(parser_name text, OUT tokid integer, OUT alias text, OUT description text)

  描述: 获取分析器定义的记号类型。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_token_type('default');
                          ts_token_type
  --------------------------------------------------------------
   (1,asciiword,"Word, all ASCII")
   (2,word,"Word, all letters")
   (3,numword,"Word, letters and digits")
   (4,email,"Email address")
   (5,url,URL)
   (6,host,Host)
   (7,sfloat,"Scientific notation")
   (8,version,"Version number")
   (9,hword_numpart,"Hyphenated word part, letters and digits")
   (10,hword_part,"Hyphenated word part, all letters")
   (11,hword_asciipart,"Hyphenated word part, all ASCII")
   (12,blank,"Space symbols")
   (13,tag,"XML tag")
   (14,protocol,"Protocol head")
   (15,numhword,"Hyphenated word, letters and digits")
   (16,asciihword,"Hyphenated word, all ASCII")
   (17,hword,"Hyphenated word, all letters")
   (18,url_path,"URL path")
   (19,file,"File or path name")
   (20,float,"Decimal notation")
   (21,int,"Signed integer")
   (22,uint,"Unsigned integer")
   (23,entity,"XML entity")
  (23 rows)

• ts_token_type(parser_oid oid, OUT tokid integer, OUT alias text, OUT description text)

  描述: 获取分析器定义的记号类型。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_token_type(3722);
                          ts_token_type
  --------------------------------------------------------------
   (1,asciiword,"Word, all ASCII")
   (2,word,"Word, all letters")
   (3,numword,"Word, letters and digits")
   (4,email,"Email address")
   (5,url,URL)
   (6,host,Host)
   (7,sfloat,"Scientific notation")
   (8,version,"Version number")
   (9,hword_numpart,"Hyphenated word part, letters and digits")
   (10,hword_part,"Hyphenated word part, all letters")
   (11,hword_asciipart,"Hyphenated word part, all ASCII")
   (12,blank,"Space symbols")
   (13,tag,"XML tag")
   (14,protocol,"Protocol head")
   (15,numhword,"Hyphenated word, letters and digits")
   (16,asciihword,"Hyphenated word, all ASCII")
   (17,hword,"Hyphenated word, all letters")
   (18,url_path,"URL path")
   (19,file,"File or path name")
   (20,float,"Decimal notation")
   (21,int,"Signed integer")
   (22,uint,"Unsigned integer")
   (23,entity,"XML entity")
  (23 rows)

• ts_stat(sqlquery text, [ weights text, ] OUT word text, OUT ndoc integer, OUT nentry integer)

  描述: 获取tsvector列的统计数据。

  返回类型: setof record

  示例:

  MogDB=# SELECT ts_stat('select ''hello world''::tsvector');
     ts_stat
  -------------
   (world,1,1)
   (hello,1,1)
  (2 rows)