Re: ICU for global collation

Hi,

On Thu, Dec 30, 2021 at 01:07:21PM +0100, Peter Eisentraut wrote:
>
> So this is a different approach: If you choose ICU as the default locale for
> a database, you still need to specify lc_ctype and lc_collate settings, as
> before. Unlike in the previous patch, where the ICU collation name was
> written in datcollate, there is now a third column (daticucoll), so we can
> store all three values. This fixes the described problem. Other than that,
> once you get all the initial settings right, it basically just works: The
> places that have ICU support now will use a database-wide ICU collation if
> appropriate, the places that don't have ICU support continue to use the
> global libc locale settings.

That looks sensible to me.

> @@ -2774,6 +2776,7 @@ dumpDatabase(Archive *fout)
> appendPQExpBuffer(dbQry, "SELECT tableoid, oid, datname, "
> "(%s datdba) AS dba, "
> "pg_encoding_to_char(encoding) AS encoding, "
> + "datcollprovider, "

This needs to be in a new pg 15+ branch, not in the pg 9.3+.

> - if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
> - mylocale = pg_newlocale_from_collation(collid);
> + if (!lc_collate_is_c(collid))
> + {
> + if (collid != DEFAULT_COLLATION_OID)
> + mylocale = pg_newlocale_from_collation(collid);
> + else if (default_locale.provider == COLLPROVIDER_ICU)
> + mylocale = &default_locale;
> + }

There are really a lot of places with this new code. Maybe it could be some
new function/macro to wrap that for the normal case (e.g. not formatting.c)?