MIME-Version: 1.0
Date: Sat, 17 Sep 2022 11:33:30 +0300
From: Marina Polyakova <m.polyakova@postgrespro.ru>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
 pgsql-hackers@postgresql.org, pryzby@telsasoft.com, rjuju123@gmail.com,
 daniel@manitou-mail.org, AndrewBille@gmail.com, michael@paquier.xyz
Subject: Re: ICU for global collation
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Thanks to Kyotaro Horiguchi review we found out that there're 
interesting cases due to the order of some ICU checks:

1. ICU locale vs supported encoding:

1.1.

On 2022-09-15 09:52, Kyotaro Horiguchi wrote:
> If I executed initdb as follows, I would be told to specify
> --icu-locale option.
> 
>> $ initdb --encoding sql-ascii --locale-provider icu hoge
>> ...
>> initdb: error: ICU locale must be specified
> 
> However, when I reran the command, it complains about incompatible
> encoding this time.  I think it's more user-friendly to check for the
> encoding compatibility before the check for missing --icu-locale
> option.

1.2. (ok?)

$ initdb --encoding sql-ascii --icu-locale en-US hoge
initdb: error: --icu-locale cannot be specified unless locale provider 
"icu" is chosen

$ initdb --encoding sql-ascii --icu-locale en-US --locale-provider icu 
hoge
...
initdb: error: encoding mismatch
initdb: detail: The encoding you selected (SQL_ASCII) is not supported 
with the ICU provider.
initdb: hint: Rerun initdb and either do not specify an encoding 
explicitly, or choose a matching combination.

$ createdb --encoding sql-ascii --icu-locale en-US hoge
createdb: error: database creation failed: ERROR:  ICU locale cannot be 
specified unless locale provider is ICU
$ createdb --encoding sql-ascii --icu-locale en-US --locale-provider icu 
hoge
createdb: error: database creation failed: ERROR:  encoding "SQL_ASCII" 
is not supported with ICU provider

2. For builds without ICU:

2.1.

$ initdb --locale-provider icu hoge
...
initdb: error: ICU locale must be specified

$ initdb --locale-provider icu --icu-locale en-US hoge
...
initdb: error: ICU is not supported in this build

$ createdb --locale-provider icu hoge
createdb: error: database creation failed: ERROR:  ICU locale must be 
specified

$ createdb --locale-provider icu --icu-locale en-US hoge
createdb: error: database creation failed: ERROR:  ICU is not supported 
in this build

IMO, it would be more user-friendly to inform an unsupported build in 
the first runs too..

2.2. (ok?)

$ initdb --icu-locale en-US hoge
initdb: error: --icu-locale cannot be specified unless locale provider 
"icu" is chosen
$ initdb --icu-locale en-US --locale-provider icu hoge
...
initdb: error: ICU is not supported in this build

$ createdb --icu-locale en-US hoge
createdb: error: database creation failed: ERROR:  ICU locale cannot be 
specified unless locale provider is ICU
$ createdb --icu-locale en-US --locale-provider icu hoge
createdb: error: database creation failed: ERROR:  ICU is not supported 
in this build

2.3.

$ createdb --locale-provider icu --icu-locale en-US --encoding sql-ascii 
hoge
createdb: error: database creation failed: ERROR:  encoding "SQL_ASCII" 
is not supported with ICU provider
$ createdb --locale-provider icu --icu-locale en-US --encoding utf8 hoge
createdb: error: database creation failed: ERROR:  ICU is not supported 
in this build

IMO, it would be more user-friendly to inform an unsupported build in 
the first run too..

3.

The locale provider is ICU, but it has not yet been set from the 
template database:

> $ initdb --locale-provider icu --icu-locale en-US -D data &&
> pg_ctl -D data -l logfile start &&
> createdb --icu-locale ru-RU --template template0 mydb
> ...
> createdb: error: database creation failed: ERROR:  ICU locale cannot be
> specified unless locale provider is ICU

-- 
Marina Polyakova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company