Add case insensitive collation to PostgreSQL

Question

By default, PostgreSQL comes without case insensitive collations. Its documentation describes a way to add new collations based on OS locales, e.g.:

http://www.postg

Answer 1

"Nondeterministic collations" were added to Version 12:

"The most typical use case for nondeterministic collations is probably the case-insensitive comparison. At secondary strength, strings that differ by case compare as equal"

Answer 2

Doesn't seem to be possible within Postgres iteself:

Not from the Postgres project -- we just use the collations supplied by the operating system.