文本检索操作符
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@@
描述：tsvector类型的词汇与tsquery类型的词汇是否匹配
示例：
``` postgres=# SELECT to_tsvector('fat cats ate rats') @@ to_tsquery('cat & rat') AS RESULT; result
t (1 row) ```
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@@@
描述：@@的同义词
示例：
``` postgres=# SELECT to_tsvector('fat cats ate rats') @@@ to_tsquery('cat & rat') AS RESULT; result
t (1 row) ```
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||
描述：连接两个tsvector类型的词汇
示例：
``` postgres=# 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) ```
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&&
描述：将两个tsquery类型的词汇进行“与”操作
示例：
``` postgres=# SELECT 'fat | rat'::tsquery && 'cat'::tsquery AS RESULT; result
( 'fat' | 'rat' ) & 'cat' (1 row) ```
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||
描述：将两个tsquery类型的词汇进行“或”操作
示例：
``` postgres=# SELECT 'fat | rat'::tsquery || 'cat'::tsquery AS RESULT; result
( 'fat' | 'rat' ) | 'cat' (1 row) ```
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!!
描述：tsquery类型词汇的非关系
示例：
``` postgres=# SELECT !! 'cat'::tsquery AS RESULT; result
!'cat' (1 row) ```
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@>
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：
``` postgres=# SELECT 'cat'::tsquery @> 'cat & rat'::tsquery AS RESULT; result
f (1 row) ```
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<@
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：
``` postgres=# 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
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get_current_ts_config()
描述：获取文本检索的默认配置。
返回类型：regconfig
示例：
``` postgres=# SELECT get_current_ts_config(); get_current_ts_config
english (1 row) ```
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length(tsvector)
描述：tsvector类型词汇的单词数。
返回类型：integer
示例：
``` postgres=# SELECT length('fat:2,4 cat:3 rat:5A'::tsvector); length
3(1 row) ```
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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：
``` postgres=# SELECT numnode('(fat & rat) | cat'::tsquery); numnode
5(1 row) ```
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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：
``` postgres=# SELECT plainto_tsquery('english', 'The Fat Rats'); plainto_tsquery
'fat' & 'rat' (1 row) ```
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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：
``` postgres=# SELECT querytree('foo & ! bar'::tsquery); querytree
'foo' (1 row) ```
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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：
``` postgres=# SELECT setweight('fat:2,4 cat:3 rat:5B'::tsvector, 'A'); setweight
'cat':3A 'fat':2A,4A 'rat':5A (1 row) ```
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strip(tsvector)
描述：删除tsvector类型单词中的position和权值。
返回类型：tsvector
示例：
``` postgres=# SELECT strip('fat:2,4 cat:3 rat:5A'::tsvector); strip
'cat' 'fat' 'rat' (1 row) ```
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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：
``` postgres=# SELECT to_tsquery('english', 'The & Fat & Rats'); to_tsquery
'fat' & 'rat' (1 row) ```
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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：
``` postgres=# SELECT to_tsvector('english', 'The Fat Rats'); to_tsvector
'fat':2 'rat':3 (1 row) ```
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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：
``` postgres=# SELECT ts_headline('x y z', 'z'::tsquery); ts_headline
x y z (1 row) ```
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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：
``` postgres=# SELECT ts_rank('hello world'::tsvector, 'world'::tsquery); ts_rank
.0607927 (1 row) ```
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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：
``` postgres=# SELECT ts_rank_cd('hello world'::tsvector, 'world'::tsquery); ts_rank_cd
.1(1 row) ```
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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：
``` postgres=# SELECT ts_rewrite('a & b'::tsquery, 'a'::tsquery, 'foo|bar'::tsquery); ts_rewrite
'b' & ( 'foo' | 'bar' ) (1 row) ```
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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：
``` postgres=# SELECT ts_rewrite('world'::tsquery, 'select ''world''::tsquery, ''hello''::tsquery'); ts_rewrite
'hello' (1 row) ```
文本检索调试函数
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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：
``` postgres=# 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) ```
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ts_lexize(dict regdictionary, token text)
描述：测试一个数据字典。
返回类型：text[]
示例：
``` postgres=# SELECT ts_lexize('english_stem', 'stars'); ts_lexize
{star} (1 row) ```
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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：
``` postgres=# SELECT ts_parse('default', 'foo - bar'); ts_parse
(1,foo) (12," ") (12,"- ") (1,bar) (4 rows) ```
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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：
``` postgres=# SELECT ts_parse(3722, 'foo - bar'); ts_parse
(1,foo) (12," ") (12,"- ") (1,bar) (4 rows) ```
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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：
``` postgres=# 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) ```
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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：
``` postgres=# 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) ```
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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：
``` postgres=# SELECT ts_stat('select ''hello world''::tsvector'); ts_stat
(world,1,1) (hello,1,1) (2 rows) ```
