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9.13. Text Search Functions and Operators

Table 9.40, Table 9.41 and Table 9.42 summarize the functions and operators that are provided for full text searching. See Chapter 12 for a detailed explanation of PostgreSQL's text search facility.

Table 9.40. Text Search Operators

Operator Return Type Description Example Result
@@ boolean tsvector matches tsquery ? to_tsvector('fat cats ate rats') @@ to_tsquery('cat & rat') t
@@@ boolean deprecated synonym for @@ to_tsvector('fat cats ate rats') @@@ to_tsquery('cat & rat') t
|| tsvector concatenate tsvectors 'a:1 b:2'::tsvector || 'c:1 d:2 b:3'::tsvector 'a':1 'b':2,5 'c':3 'd':4
&& tsquery AND tsquerys together 'fat | rat'::tsquery && 'cat'::tsquery ( 'fat' | 'rat' ) & 'cat'
|| tsquery OR tsquerys together 'fat | rat'::tsquery || 'cat'::tsquery ( 'fat' | 'rat' ) | 'cat'
!! tsquery negate a tsquery !! 'cat'::tsquery !'cat'
<-> tsquery tsquery followed by tsquery to_tsquery('fat') <-> to_tsquery('rat') 'fat' <-> 'rat'
@> boolean tsquery contains another ? 'cat'::tsquery @> 'cat & rat'::tsquery f
<@ boolean tsquery is contained in ? 'cat'::tsquery <@ 'cat & rat'::tsquery t

Note

The tsquery containment operators consider only the lexemes listed in the two queries, ignoring the combining operators.

In addition to the operators shown in the table, the ordinary B-tree comparison operators (=, <, etc) are defined for types tsvector and tsquery. These are not very useful for text searching but allow, for example, unique indexes to be built on columns of these types.

Table 9.41. Text Search Functions

Function Return Type Description Example Result
array_to_tsvector(text[]) tsvector convert array of lexemes to tsvector array_to_tsvector('{fat,cat,rat}'::text[]) 'cat' 'fat' 'rat'
get_current_ts_config() regconfig get default text search configuration get_current_ts_config() english
length(tsvector) integer number of lexemes in tsvector length('fat:2,4 cat:3 rat:5A'::tsvector) 3
numnode(tsquery) integer number of lexemes plus operators in tsquery numnode('(fat & rat) | cat'::tsquery) 5
plainto_tsquery([ config regconfig , ] query text) tsquery produce tsquery ignoring punctuation plainto_tsquery('english', 'The Fat Rats') 'fat' & 'rat'
phraseto_tsquery([ config regconfig , ] query text) tsquery produce tsquery that searches for a phrase, ignoring punctuation phraseto_tsquery('english', 'The Fat Rats') 'fat' <-> 'rat'
websearch_to_tsquery([ config regconfig , ] query text) tsquery produce tsquery from a web search style query websearch_to_tsquery('english', '"fat rat" or rat') 'fat' <-> 'rat' | 'rat'
querytree(query tsquery) text get indexable part of a tsquery querytree('foo & ! bar'::tsquery) 'foo'
setweight(vector tsvector, weight "char") tsvector assign weight to each element of vector setweight('fat:2,4 cat:3 rat:5B'::tsvector, 'A') 'cat':3A 'fat':2A,4A 'rat':5A
setweight(vector tsvector, weight "char", lexemes text[]) tsvector assign weight to elements of vector that are listed in lexemes setweight('fat:2,4 cat:3 rat:5B'::tsvector, 'A', '{cat,rat}') 'cat':3A 'fat':2,4 'rat':5A
strip(tsvector) tsvector remove positions and weights from tsvector strip('fat:2,4 cat:3 rat:5A'::tsvector) 'cat' 'fat' 'rat'
to_tsquery([ config regconfig , ] query text) tsquery normalize words and convert to tsquery to_tsquery('english', 'The & Fat & Rats') 'fat' & 'rat'
to_tsvector([ config regconfig , ] document text) tsvector reduce document text to tsvector to_tsvector('english', 'The Fat Rats') 'fat':2 'rat':3
to_tsvector([ config regconfig , ] document json(b)) tsvector reduce each string value in the document to a tsvector, and then concatenate those in document order to produce a single tsvector to_tsvector('english', '{"a": "The Fat Rats"}'::json) 'fat':2 'rat':3
json(b)_to_tsvector([ config regconfig, ] document json(b), filter json(b)) tsvector reduce each value in the document, specified by filter to a tsvector, and then concatenate those in document order to produce a single tsvector. filter is a jsonb array, that enumerates what kind of elements need to be included into the resulting tsvector. Possible values for filter are "string" (to include all string values), "numeric" (to include all numeric values in the string format), "boolean" (to include all Boolean values in the string format "true"/"false"), "key" (to include all keys) or "all" (to include all above). These values can be combined together to include, e.g., all string and numeric values. json_to_tsvector('english', '{"a": "The Fat Rats", "b": 123}'::json, '["string", "numeric"]') '123':5 'fat':2 'rat':3
ts_delete(vector tsvector, lexeme text) tsvector remove given lexeme from vector ts_delete('fat:2,4 cat:3 rat:5A'::tsvector, 'fat') 'cat':3 'rat':5A
ts_delete(vector tsvector, lexemes text[]) tsvector remove any occurrence of lexemes in lexemes from vector ts_delete('fat:2,4 cat:3 rat:5A'::tsvector, ARRAY['fat','rat']) 'cat':3
ts_filter(vector tsvector, weights "char"[]) tsvector select only elements with given weights from vector ts_filter('fat:2,4 cat:3b rat:5A'::tsvector, '{a,b}') 'cat':3B 'rat':5A
ts_headline([ config regconfig, ] document text, query tsquery [, options text ]) text display a query match ts_headline('x y z', 'z'::tsquery) x y <b>z</b>
ts_headline([ config regconfig, ] document json(b), query tsquery [, options text ]) text display a query match ts_headline('{"a":"x y z"}'::json, 'z'::tsquery) {"a":"x y <b>z</b>"}
ts_rank([ weights float4[], ] vector tsvector, query tsquery [, normalization integer ]) float4 rank document for query ts_rank(textsearch, query) 0.818
ts_rank_cd([ weights float4[], ] vector tsvector, query tsquery [, normalization integer ]) float4 rank document for query using cover density ts_rank_cd('{0.1, 0.2, 0.4, 1.0}', textsearch, query) 2.01317
ts_rewrite(query tsquery, target tsquery, substitute tsquery) tsquery replace target with substitute within query ts_rewrite('a & b'::tsquery, 'a'::tsquery, 'foo|bar'::tsquery) 'b' & ( 'foo' | 'bar' )
ts_rewrite(query tsquery, select text) tsquery replace using targets and substitutes from a SELECT command SELECT ts_rewrite('a & b'::tsquery, 'SELECT t,s FROM aliases') 'b' & ( 'foo' | 'bar' )
tsquery_phrase(query1 tsquery, query2 tsquery) tsquery make query that searches for query1 followed by query2 (same as <-> operator) tsquery_phrase(to_tsquery('fat'), to_tsquery('cat')) 'fat' <-> 'cat'
tsquery_phrase(query1 tsquery, query2 tsquery, distance integer) tsquery make query that searches for query1 followed by query2 at distance distance tsquery_phrase(to_tsquery('fat'), to_tsquery('cat'), 10) 'fat' <10> 'cat'
tsvector_to_array(tsvector) text[] convert tsvector to array of lexemes tsvector_to_array('fat:2,4 cat:3 rat:5A'::tsvector) {cat,fat,rat}
tsvector_update_trigger() trigger trigger function for automatic tsvector column update CREATE TRIGGER ... tsvector_update_trigger(tsvcol, 'pg_catalog.swedish', title, body)
tsvector_update_trigger_column() trigger trigger function for automatic tsvector column update CREATE TRIGGER ... tsvector_update_trigger_column(tsvcol, configcol, title, body)
unnest(tsvector, OUT lexeme text, OUT positions smallint[], OUT weights text) setof record expand a tsvector to a set of rows unnest('fat:2,4 cat:3 rat:5A'::tsvector) (cat,{3},{D}) ...

Note

All the text search functions that accept an optional regconfig argument will use the configuration specified by default_text_search_config when that argument is omitted.

The functions in Table 9.42 are listed separately because they are not usually used in everyday text searching operations. They are helpful for development and debugging of new text search configurations.

Table 9.42. Text Search Debugging Functions

Function Return Type Description Example Result
ts_debug([ config regconfig, ] document text, OUT alias text, OUT description text, OUT token text, OUT dictionaries regdictionary[], OUT dictionary regdictionary, OUT lexemes text[]) setof record test a configuration ts_debug('english', 'The Brightest supernovaes') (asciiword,"Word, all ASCII",The,{english_stem},english_stem,{}) ...
ts_lexize(dict regdictionary, token text) text[] test a dictionary ts_lexize('english_stem', 'stars') {star}
ts_parse(parser_name text, document text, OUT tokid integer, OUT token text) setof record test a parser ts_parse('default', 'foo - bar') (1,foo) ...
ts_parse(parser_oid oid, document text, OUT tokid integer, OUT token text) setof record test a parser ts_parse(3722, 'foo - bar') (1,foo) ...
ts_token_type(parser_name text, OUT tokid integer, OUT alias text, OUT description text) setof record get token types defined by parser ts_token_type('default') (1,asciiword,"Word, all ASCII") ...
ts_token_type(parser_oid oid, OUT tokid integer, OUT alias text, OUT description text) setof record get token types defined by parser ts_token_type(3722) (1,asciiword,"Word, all ASCII") ...
ts_stat(sqlquery text, [ weights text, ] OUT word text, OUT ndoc integer, OUT nentry integer) setof record get statistics of a tsvector column ts_stat('SELECT vector from apod') (foo,10,15) ...