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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2025-08-26 12:49:44 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2025-08-26 13:22:43 +0300 |
| commit | f8ce9ed220b5edd8ba751706bbcdbcc5b64be66e (patch) | |
| tree | 0dae20833b918e3800a6a2914e741900f0c2732b | |
| parent | f5e0186f865cc188ef6f4b2bc77d0c028f78195e (diff) | |
Further clarify documentation for the initcap function
This is a follow-up for commit c2c2c7e225. It further clarifies the
following in the initcap function documentation:
* Document that title case is used for digraphs in specific locales,
* Reference particular ICU function used,
* Add note about the purpose of the function.
Discussion: https://postgr.es/m/804cc10ef95d4d3b298e76b181fd9437%40postgrespro.ru
Author: Oleg Tselebrovskiy <o.tselebrovskiy@postgrespro.ru>
Co-authored-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Jeff Davis <pgsql@j-davis.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
| -rw-r--r-- | doc/src/sgml/func/func-string.sgml | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/doc/src/sgml/func/func-string.sgml b/doc/src/sgml/func/func-string.sgml index 3eec93eb339..01cc94c234e 100644 --- a/doc/src/sgml/func/func-string.sgml +++ b/doc/src/sgml/func/func-string.sgml @@ -693,12 +693,21 @@ <returnvalue>text</returnvalue> </para> <para> - Converts the first letter of each word to upper case and the - rest to lower case. When using the <literal>libc</literal> locale - provider, words are sequences of alphanumeric characters separated - by non-alphanumeric characters; when using the ICU locale provider, - words are separated according to - <ulink url="https://www.unicode.org/reports/tr29/#Word_Boundaries">Unicode Standard Annex #29</ulink>. + Converts the first letter of each word to upper case (or title case + if the letter is a digraph and locale is <literal>ICU</literal> or + <literal>builtin</literal> <literal>PG_UNICODE_FAST</literal>) + and the rest to lower case. When using the <literal>libc</literal> or + <literal>builtin</literal> locale provider, words are sequences of + alphanumeric characters separated by non-alphanumeric characters; + when using the ICU locale provider, words are separated according to + <ulink url="https://unicode-org.github.io/icu-docs/apidoc/dev/icu4c/ustring_8h.html#a47602e2c2012d77ee91908b9bbfdc063">u_strToTitle ICU function</ulink>. + </para> + <para> + This function is primarily used for convenient + display, and the specific result should not be relied upon because of + the differences between locale providers and between different + ICU versions. If specific word boundary rules are desired, + it is recommended to write a custom function. </para> <para> <literal>initcap('hi THOMAS')</literal> |