12.8. 测试和调试文本搜索

一个自定义文本搜索配置的行为很容易变得混乱。本节中描述的函数对于测试文本搜索对象有用。你可以测试一个完整的配置,或者独立测试解析器和词典。

12.8.1. 配置测试

函数ts_debug允许简单地测试一个文本搜索配置。

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

ts_debug显示document的每一个记号的信息,记号由解析器产生并由配置的词典处理过。该函数使用由config指定的配置,如果该参数被忽略则使用default_text_search_config指定的配置。

ts_debug为解析器在文本中标识的每一个记号返回一行。被返回的列是:

这里是一个简单的例子:

SELECT * FROM ts_debug('english','a fat  cat sat on a mat - it ate a fat rats');
   alias   |   description   | token |  dictionaries  |  dictionary  | lexemes 
-----------+-----------------+-------+----------------+--------------+---------
 asciiword | Word, all ASCII | a     | {english_stem} | english_stem | {}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | fat   | {english_stem} | english_stem | {fat}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | cat   | {english_stem} | english_stem | {cat}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | sat   | {english_stem} | english_stem | {sat}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | on    | {english_stem} | english_stem | {}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | a     | {english_stem} | english_stem | {}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | mat   | {english_stem} | english_stem | {mat}
 blank     | Space symbols   |       | {}             |              | 
 blank     | Space symbols   | -     | {}             |              | 
 asciiword | Word, all ASCII | it    | {english_stem} | english_stem | {}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | ate   | {english_stem} | english_stem | {ate}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | a     | {english_stem} | english_stem | {}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | fat   | {english_stem} | english_stem | {fat}
 blank     | Space symbols   |       | {}             |              | 
 asciiword | Word, all ASCII | rats  | {english_stem} | english_stem | {rat}

为了一个更广泛的示范,我们先为英语语言创建一个public.english配置和 Ispell 词典:

CREATE TEXT SEARCH CONFIGURATION public.english ( COPY = pg_catalog.english );

CREATE TEXT SEARCH DICTIONARY english_ispell (
    TEMPLATE = ispell,
    DictFile = english,
    AffFile = english,
    StopWords = english
);

ALTER TEXT SEARCH CONFIGURATION public.english
   ALTER MAPPING FOR asciiword WITH english_ispell, english_stem;
SELECT * FROM ts_debug('public.english','The Brightest supernovaes');
   alias   |   description   |    token    |         dictionaries          |   dictionary   |   lexemes   
-----------+-----------------+-------------+-------------------------------+----------------+-------------
 asciiword | Word, all ASCII | The         | {english_ispell,english_stem} | english_ispell | {}
 blank     | Space symbols   |             | {}                            |                | 
 asciiword | Word, all ASCII | Brightest   | {english_ispell,english_stem} | english_ispell | {bright}
 blank     | Space symbols   |             | {}                            |                | 
 asciiword | Word, all ASCII | supernovaes | {english_ispell,english_stem} | english_stem   | {supernova}

在这个例子中,词Brightest被解析器识别为一个ASCII 词(别名asciiword)。对于这种记号类型,词典列表是english_ispellenglish_stem。该词被english_ispell识别,这个词典将它缩减为名词bright。词supernovaes对于english_ispell词典是未知的,因此它被传递给下一个词典,并且幸运地是,它被识别了(实际上,english_stem是一个 Snowball 词典,它识别所有的东西;这也是为什么它被放置在词典列表的尾部)。

Theenglish_ispell词典识别为一个停用词(Section 12.6.1)并且将不会被索引。空格也被丢弃,因为该配置没有为它们提供词典。

你可以通过显式地指定你想看哪些列来缩减输出的宽度:

SELECT alias, token, dictionary, lexemes
FROM ts_debug('public.english','The Brightest supernovaes');
   alias   |    token    |   dictionary   |   lexemes   
-----------+-------------+----------------+-------------
 asciiword | The         | english_ispell | {}
 blank     |             |                | 
 asciiword | Brightest   | english_ispell | {bright}
 blank     |             |                | 
 asciiword | supernovaes | english_stem   | {supernova}

12.8.2. 解析器测试

下列函数允许直接测试一个文本搜索解析器。

ts_parse(parser_name text, document text,
         OUT tokid integer, OUT token text) returns setof record
ts_parse(parser_oid oid, document text,
         OUT tokid integer, OUT token text) returns setof record

ts_parse解析给定的document并返回一系列记录,每一个记录对应一个由解析产生的记号。每一个记录包括一个tokid展示分配给记号的类型以及一个token展示记号的文本。例如:

SELECT * FROM ts_parse('default', '123 - a number');
 tokid | token
-------+--------
    22 | 123
    12 |
    12 | -
     1 | a
    12 |
     1 | number

ts_token_type(parser_name text, OUT tokid integer,
              OUT alias text, OUT description text) returns setof record
ts_token_type(parser_oid oid, OUT tokid integer,
              OUT alias text, OUT description text) returns setof record

ts_token_type返回一个表,该表描述指定解析器能够识别的每一种记号类型。对于每一种记号类型,该表给出了解析器用来标注该类型记号的整数tokid,还给出了在配置命令中命名该记号类型的alias,以及一个简短的description。例如:

SELECT * FROM ts_token_type('default');
 tokid |      alias      |               description                
-------+-----------------+------------------------------------------
     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

12.8.3. 词典测试

ts_lexize函数帮助词典测试。

ts_lexize(dict regdictionary, token text) returns text[]

如果输入的token是该词典已知的,则ts_lexize返回一个词位数组;如果记号是词典已知的但是它是一个停用词,则返回一个空数组;或者如果它对词典是未知词,则返回NULL

例子:

SELECT ts_lexize('english_stem', 'stars');
 ts_lexize
-----------
 {star}

SELECT ts_lexize('english_stem', 'a');
 ts_lexize
-----------
 {}

Note: ts_lexize函数期望一个单一记号而不是文本。下面的情况会让它搞混:

SELECT ts_lexize('thesaurus_astro','supernovae stars') is null;
 ?column?
----------
 t

分类词典thesaurus_astro确实知道短语supernovae stars,但是ts_lexize会失败,因为它无法解析输入文本而把它当做一个单一记号。可以使用plainto_tsqueryto_tsvector来测试分类词典,例如:

SELECT plainto_tsquery('supernovae stars');
 plainto_tsquery
-----------------
 'sn'