Text Search Functions and Operators

Text Search Operators

Description: Specifies whether the tsvector-type words match the tsquery-type words.

Example:

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

@@@

Description: Synonym for @@

Example:

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

Description: Connects two tsvector-type words.

Example:

openGauss=# 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)

Description: Performs an AND operation on two tsquery-type words.

Example:

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

Description: Performs an OR operation on two tsquery-type words.

Example:

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

Description: NOT a tsquery

Example:

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

Description: Specifies whether a tsquery-type word contains another tsquery-type word.

Example:

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

<@
Description: Specifies whether a tsquery-type word is contained in another tsquery-type word.
Example:
```
openGauss=# SELECT 'cat'::tsquery <@ 'cat & rat'::tsquery AS RESULT;
 result 
--------
 t
(1 row)
```

In addition to the preceding operators, the ordinary B-tree comparison operators (including = and <) are defined for types tsvector and tsquery.

Text Search Functions

get_current_ts_config()

Description: Obtains default text search configurations.

Return type: regconfig

Example:

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

length(tsvector)
Description: Specifies the number of lexemes in a tsvector-type word.
Return type: integer
Example:
```
openGauss=# SELECT length('fat:2,4 cat:3 rat:5A'::tsvector);
 length 
--------
      3
(1 row)
```
numnode(tsquery)
Description: Specifies the number of lexemes plus tsquery operators.
Return type: integer
Example:
```
openGauss=# SELECT numnode('(fat & rat) | cat'::tsquery);
 numnode 
---------
       5
(1 row)
```
plainto_tsquery([ config regconfig , ] query text)
Description: Generates tsquery lexemes without punctuations.
Return type: tsquery
Example:
```
openGauss=# SELECT plainto_tsquery('english', 'The Fat Rats');
 plainto_tsquery 
-----------------
 'fat' & 'rat'
(1 row)
```
querytree(query tsquery)
Description: Obtains the indexable part of a tsquery.
Return type: text
Example:
```
openGauss=# SELECT querytree('foo & ! bar'::tsquery);
 querytree 
-----------
 'foo'
(1 row)
```

setweight(tsvector, “char”)

Description: Assigns weight to each element of tsvector.

Return type: tsvector

Example:

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

strip(tsvector)

Description: Removes positions and weights from tsvector.

Return type: tsvector

Example:

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

to_tsquery([ config regconfig , ] query text)
Description: Normalizes words and converts them to tsquery.
Return type: tsquery
Example:
```
openGauss=# SELECT to_tsquery('english', 'The & Fat & Rats');
  to_tsquery   
---------------
 'fat' & 'rat'
(1 row)
```
to_tsvector([ config regconfig , ] document text)
Description: Reduces document text to tsvector.
Return type: tsvector
Example:
```
openGauss=# SELECT to_tsvector('english', 'The Fat Rats');
   to_tsvector   
-----------------
 'fat':2 'rat':3
(1 row)
```
to_tsvector_for_batch([ config regconfig , ] document text)
Description: Reduces document text to tsvector.
Return type: tsvector
Example:
```
openGauss=# 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 ])
Description: Highlights a query match.
Return type: text
Example:
```
openGauss=# 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 ])
Description: Ranks documents for a query.
Return type: float4
Example:
```
openGauss=# SELECT ts_rank('hello world'::tsvector, 'world'::tsquery);
 ts_rank  
----------
 .0607927
(1 row)
```
ts_rank_cd([ weights float4[], ] vector tsvector, query tsquery [, normalization integer ])
Description: Ranks documents for a query using cover density.
Return type: float4
Example:
```
openGauss=# SELECT ts_rank_cd('hello world'::tsvector, 'world'::tsquery);
 ts_rank_cd 
------------
          .1
(1 row)
```

ts_rewrite(query tsquery, target tsquery, substitute tsquery)

Description: Replaces a tsquery-type word.

Return type: tsquery

Example:

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

ts_rewrite(query tsquery, select text)
Description: Replaces tsquery data in the target with the result of a SELECT command.
Return type: tsquery
Example:
```
openGauss=# SELECT ts_rewrite('world'::tsquery, 'select ''world''::tsquery, ''hello''::tsquery');
 ts_rewrite 
------------
 'hello'
(1 row)
```

Text Search Debugging Functions

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

Description: Tests a configuration.

Return type: SETOF record

Example:

openGauss=# 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)
Description: Tests a data dictionary.
Return type: text[]
Example:
```
openGauss=# SELECT ts_lexize('english_stem', 'stars');
 ts_lexize 
-----------
 {star}
(1 row)
```
ts_parse(parser_name text, document text, OUT tokid integer, OUT token text)
Description: Tests a parser.
Return type: SETOF record
Example:
```
openGauss=# 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)
Description: Tests a parser.
Return type: SETOF record
Example:
```
openGauss=# 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)

Description: Obtains token types defined by a parser.

Return type: SETOF record

Example:

openGauss=# 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)

Description: Obtains token types defined by a parser.

Return type: SETOF record

Example:

openGauss=# 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)
Description: Obtains statistics of a tsvector column.
Return type: SETOF record
Example:
```
openGauss=# SELECT ts_stat('select ''hello world''::tsvector');
   ts_stat   
-------------
 (world,1,1)
 (hello,1,1)
(2 rows)
```