Re: unicode match normal forms

[Gianni Ceccarelli]

On 17 May 2021 13:27:40 -0000
haman...@t-online.de wrote:
> in unicode letter ä exists in two versions - linux and windows use a
> composite whereas macos prefers the decomposed form. Is there any
> way to make a semi-exact match that accepts both variants?

Actually, re-reading your request, you want to *find* both forms?

In which case, a function index may be more useful::

  create index filename_unique_normalized
  on that_table(normalize(filename));

then you can search::

  select *
  from that_table
  where normalize(filename)=?

If you want to make sure that no two rows contain "equally-looking"
filenames, you can use a unique index::

  create unique index filename_unique_normalized
  on that_table(normalize(filename));

(while we're on the topic of "equally-looking" characters, you may
want to look at https://en.wikipedia.org/wiki/Homoglyph and
https://www.unicode.org/reports/tr36/ )

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