Help Center/ GaussDB(DWS)/ SQL Syntax Reference/ SQL Syntax Reference (8.1.3.x)/ Functions and Operators/ Text Search Functions and Operators/ Text Search Functions
Updated on 2024-09-03 GMT+08:00
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Text Search Functions

get_current_ts_config()

Description: Gets default text search configuration.

Return type: regconfig

Example:

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SELECT get_current_ts_config();
 get_current_ts_config 
-----------------------
 english
(1 row)

length(tsvector)

Description: Number of lexemes in a tsvector-typed word.

Return type: integer

Example:

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

numnode(tsquery)

Description: Number of lexemes plus tsquery operators

Return type: integer

Example:

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

plainto_tsquery([ config regconfig , ] query text)

Description: Generates tsquery lexemes without punctuation.

Return type: tsquery

Example:

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

querytree(query tsquery)

Description: Gets indexable part of a tsquery.

Return type: text

Example:

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

setweight(tsvector, "char")

Description: Assigns weight to each element of tsvector.

Return type: tsvector

Example:

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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:

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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:

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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:

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SELECT to_tsvector('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:

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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 document for query.

Return type: float4

Example:

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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 document for query using cover density.

Return type: float4

Example:

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SELECT ts_rank_cd('hello world'::tsvector, 'world'::tsquery);
 ts_rank_cd 
------------
          0
(1 row)

ts_rewrite(query tsquery, target tsquery, substitute tsquery)

Description: Replaces tsquery-typed word.

Return type: tsquery

Example:

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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:

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