Clarify documentation for the initcap function

akorotkov · akorotkov · commit 1fe9e3822c4e · 2025-07-29T10:43:28.000+03:00
This commit documents differences in the definition of word separators for the initcap function between libc and ICU locale providers. Backpatch to all supported branches. Discussion: https://postgr.es/m/804cc10ef95d4d3b298e76b181fd9437%40postgrespro.ru Author: Oleg Tselebrovskiy <o.tselebrovskiy@postgrespro.ru> Backpatch-through: 13
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
@@ -3148,8 +3148,11 @@ SELECT NOT(ROW(table.*) IS NOT NULL) FROM TABLE; -- detect at least one null in
        </para>
        <para>
         Converts the first letter of each word to upper case and the
-        rest to lower case. Words are sequences of alphanumeric
-        characters separated by non-alphanumeric characters.
+        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>.
        </para>
        <para>
         <literal>initcap('hi THOMAS')</literal>
