9.13. 文字檢索函式及運算子
Table 9.40,Table 9.41andTable 9.42summarize the functions and operators that are provided for full text searching. SeeChapter 12for a detailed explanation ofPostgreSQL's text search facility.
Table 9.40. Text Search Operators
Operator | Return Type | Description | Example | Result | Text | Text | Text | Text | Text | Text | Text |
|---|---|---|---|---|---|---|---|---|---|---|---|
@@ | boolean | tsvectormatchestsquery? | 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 | tsqueryfollowed bytsquery | to_tsquery('fat') <-> to_tsquery('rat') | 'fat' <-> 'rat' | | | | | | | |
@> | boolean | tsquerycontains another ? | 'cat'::tsquery @> 'cat & rat'::tsquery | f | | | | | | | |
<@ | boolean | tsqueryis contained in ? | 'cat'::tsquery <@ 'cat & rat'::tsquery | t | | | | | | | |
The
tsquerycontainment 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 typestsvectorandtsquery. 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 | Text | Text |
|---|---|---|---|---|---|---|
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([configregconfig,]querytext) | tsquery | produce tsqueryignoring punctuation | plainto_tsquery('english', 'The Fat Rats') | 'fat' & 'rat' | | |
phraseto_tsquery([configregconfig,]querytext) | tsquery | produce tsquerythat searches for a phrase, ignoring punctuation | phraseto_tsquery('english', 'The Fat Rats') | 'fat' <-> 'rat' | | |
querytree(querytsquery) | text | get indexable part of a tsquery | querytree('foo & ! bar'::tsquery) | 'foo' | | |
setweight(vectortsvector,weight"char") | tsvector | assign weight_to each element ofvector_ | setweight('fat:2,4 cat:3 rat:5B'::tsvector, 'A') | 'cat':3A 'fat':2A,4A 'rat':5A | | |
setweight(vectortsvector,weight"char",lexemestext[]) | tsvector | assign weight_to elements ofvectorthat are listed inlexemes_ | 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([configregconfig,]querytext) | tsquery | normalize words and convert to tsquery | to_tsquery('english', 'The & Fat & Rats') | 'fat' & 'rat' | | |
to_tsvector([configregconfig,]documenttext) | tsvector | reduce document text to tsvector | to_tsvector('english', 'The Fat Rats') | 'fat':2 'rat':3 | | |
to_tsvector([configregconfig,]documentjson(b)) | tsvector | reduce each string value in the document to a tsvector, and then concatentate those in document order to produce a singletsvector | to_tsvector('english', '{"a": "The Fat Rats"}'::json) | 'fat':2 'rat':3 | | |
ts_delete(vectortsvector,lexemetext) | tsvector | remove given lexeme_fromvector_ | ts_delete('fat:2,4 cat:3 rat:5A'::tsvector, 'fat') | 'cat':3 'rat':5A | | |
ts_delete(vectortsvector,lexemestext[]) | tsvector | remove any occurrence of lexemes in lexemes_fromvector_ | ts_delete('fat:2,4 cat:3 rat:5A'::tsvector, ARRAY['fat','rat']) | 'cat':3 | | |
ts_filter(vectortsvector,weights"char"[]) | tsvector | select only elements with given weights_fromvector_ | ts_filter('fat:2,4 cat:3b rat:5A'::tsvector, '{a,b}') | 'cat':3B 'rat':5A | | |
ts_headline([configregconfig,]documenttext,querytsquery[,optionstext]) | text | display a query match | ts_headline('x y z', 'z'::tsquery) | x y <b>z</b> | | |
ts_headline([configregconfig,]documentjson(b),querytsquery[,optionstext]) | text | display a query match | ts_headline('{"a":"x y z"}'::json, 'z'::tsquery) | {"a":"x y <b>z</b>"} | | |
ts_rank([weightsfloat4[],]vectortsvector,querytsquery[,normalizationinteger]) | float4 | rank document for query | ts_rank(textsearch, query) | 0.818 | | |
ts_rank_cd([weightsfloat4[],]vectortsvector,querytsquery[,normalizationinteger]) | 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(querytsquery,targettsquery,substitutetsquery) | tsquery | replace target_withsubstitute_within query | `ts_rewrite('a & b'::tsquery, 'a'::tsquery, 'foo | bar'::tsquery)` | `'b' & ( 'foo' | 'bar' )` |
ts_rewrite(querytsquery,selecttext) | tsquery | replace using targets and substitutes from a SELECTcommand | SELECT ts_rewrite('a & b'::tsquery, 'SELECT t,s FROM aliases') | `'b' & ( 'foo' | 'bar' )` | |
tsquery_phrase(query1tsquery,query2tsquery) | tsquery | make query that searches for query1_followed byquery2_(same as<->operator) | tsquery_phrase(to_tsquery('fat'), to_tsquery('cat')) | 'fat' <-> 'cat' | | |
tsquery_phrase(query1tsquery,query2tsquery,distanceinteger) | tsquery | make query that searches for query1_followed byquery2at distancedistance_ | tsquery_phrase(to_tsquery('fat'), to_tsquery('cat'), 10) | 'fat' <10> 'cat' | | |
tsvector_to_array(tsvector) | text[] | convert tsvectorto 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 tsvectorcolumn update | CREATE TRIGGER ... tsvector_update_trigger(tsvcol, 'pg_catalog.swedish', title, body) | | | |
tsvector_update_trigger_column() | trigger | trigger function for automatic tsvectorcolumn update | CREATE TRIGGER ... tsvector_update_trigger_column(tsvcol, configcol, title, body) | | | |
unnest(tsvector, OUTlexemetext, OUTpositionssmallint[], OUTweightstext) | setof record | expand a tsvector to a set of rows | unnest('fat:2,4 cat:3 rat:5A'::tsvector) | (cat,{3},{D}) ... | | |
All the text search functions that accept an optional
regconfigargument will use the configuration specified bydefault_text_search_configwhen that argument is omitted.The functions inTable 9.42are 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([configregconfig,]documenttext, OUTaliastext, OUTdescriptiontext, OUTtokentext, OUTdictionariesregdictionary[], OUTdictionaryregdictionary, OUTlexemestext[]) | setof record | test a configuration | ts_debug('english', 'The Brightest supernovaes') | (asciiword,"Word, all ASCII",The,{english_stem},english_stem,{}) ... |
ts_lexize(dictregdictionary,tokentext) | text[] | test a dictionary | ts_lexize('english_stem', 'stars') | {star} |
ts_parse(parser_nametext,documenttext, OUTtokidinteger, OUTtokentext) | setof record | test a parser | ts_parse('default', 'foo - bar') | (1,foo) ... |
ts_parse(parser_oidoid,documenttext, OUTtokidinteger, OUTtokentext) | setof record | test a parser | ts_parse(3722, 'foo - bar') | (1,foo) ... |
ts_token_type(parser_nametext, OUTtokidinteger, OUTaliastext, OUTdescriptiontext) | setof record | get token types defined by parser | ts_token_type('default') | (1,asciiword,"Word, all ASCII") ... |
ts_token_type(parser_oidoid, OUTtokidinteger, OUTaliastext, OUTdescriptiontext) | setof record | get token types defined by parser | ts_token_type(3722) | (1,asciiword,"Word, all ASCII") ... |
ts_stat(sqlquerytext, [weightstext,] OUTwordtext, OUTndocinteger, OUTnentryinteger) | setof record | get statistics of a tsvectorcolumn | ts_stat('SELECT vector from apod') | (foo,10,15) ... |