有多字节感知的Postgresql Levenshtein吗？

本文介绍了有多字节感知的Postgresql Levenshtein吗？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 当我将 fuzzystrmatch levenshtein 函数与变音符号一起使用时，它会返回错误的/忽略多字节的结果：When I use the fuzzystrmatch levenshtein function with diacritic characters it returns a wrong / multibyte-ignorant result:select levenshtein('ą', 'x');levenshtein ------------- 2（注意：第一个字符是下面带有变音符号的'a'，在我将其复制到此处后无法正确显示）(Note: the first character is an 'a' with a diacritic below, it is not rendered properly after I copied it here) strong> fuzzystrmatch 文档（ https://www.postgresql.org/docs /9.1/fuzzystrmatch.html ）警告：The fuzzystrmatch documentation (https://www.postgresql.org/docs/9.1/fuzzystrmatch.html) warns that:但是它没有命名 levenshtein strong>功能，我想知道是否有 levenshtein 的多字节感知版本。But as it does not name the levenshtein function, I was wondering if there is a multibyte aware version of levenshtein.我知道我可以使用 unaccent 作为解决方法，但我需要保留变音符号。I know that I could use unaccent function as a workaround but I need to keep the diacritics.推荐答案 带变音符号的'a'是字符序列，即a a 和组合字符的变音符号̨： E'a\u0328' The 'a' with a diacritic is a character sequence, i.e. a combination of a and a combining character, the diacritic ̨ : E'a\u0328'有一个等效的预组合字符±： E'\u0105' There is an equivalent precomposed character ą: E'\u0105'一种解决方案是规范化 Unicode字符串，即转换组合字符A solution would be to normalise the Unicode strings, i.e. to convert the combining character sequence into the precomposed character before comparing them.不幸的是，Postgres似乎没有内置的Unicode规范化功能，但是您可以通过 PL / Perl 或 PL / Python 语言扩展。Unfortunately, Postgres doesn't seem to have a built-in Unicode normalisation function, but you can easily access one via the PL/Perl or PL/Python language extensions.例如：create extension plpythonu;create or replace function unicode_normalize(str text) returns text as $$ import unicodedata return unicodedata.normalize('NFC', str.decode('UTF-8'))$$ language plpythonu;现在，作为字符序列 E'a\u0328' unicode_normalize （levenshtein），将code>映射到等效的预组合字符 E'\u0105'距离是正确的：Now, as the character sequence E'a\u0328' is mapped onto the equivalent precomposed character E'\u0105' by using unicode_normalize, the levenshtein distance is correct:select levenshtein(unicode_normalize(E'a\u0328'), 'x');levenshtein------------- 1 这篇关于有多字节感知的Postgresql Levenshtein吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！