Date: Tue, 4 Jan 2022 10:21:04 +0800
From: Julien Rouhaud <rjuju123@gmail.com>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>,
	Daniel Verite <daniel@manitou-mail.org>
Subject: Re: ICU for global collation
Message-ID: <YdOvEAFGbfGY/47A@jrouhaud>
References: <374f8048-9d87-462c-a8aa-d02ffca6525f@manitou-mail.org>
 <d7060bf1-177c-e0f2-f13f-b857cdd1182e@2ndquadrant.com>
 <525ef44f-52bf-505f-a491-07835d039424@enterprisedb.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <525ef44f-52bf-505f-a491-07835d039424@enterprisedb.com>
Archived-At: 
 <https://www.postgresql.org/message-id/YdOvEAFGbfGY/47A%40jrouhaud>
Precedence: bulk

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)?