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Message-ID: <71cd4015-9002-4173-bd9a-075f7afb3c20@aklaver.com>
Date: Sun, 19 Apr 2026 14:21:22 -0700
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Subject: Re: List of encodings
To: Igor Korot <ikorot01@gmail.com>,
 "David G. Johnston" <david.g.johnston@gmail.com>
Cc: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
In-Reply-To: <CA+FnnTymNs9_3pBci01_Uu5OTNJFngOhu8_khpmUs88V8kX86Q@mail.gmail.com>
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On 4/19/26 1:27 PM, Igor Korot wrote:
> Hi, David,
> 
> On Sat, Apr 18, 2026 at 2:19 AM David G. Johnston
> <david.g.johnston@gmail.com> wrote:
>>
>> On Friday, April 17, 2026, Igor Korot <ikorot01@gmail.com> wrote:
>>>
>>> Hi, ALL,
>>> Does the list shown in
>>> https://www.postgresql.org/docs/current/multibyte.html#MULTIBYTE-CHARSET-SUPPORTED
>>> stored somewhere in INFORMATION_SCHEMA?
>>
>>
>> This wouldn’t be under the purview of information schema.  You can find pg-specific pieces though:
>>
>> https://www.postgresql.org/docs/current/catalog-pg-conversion.html
>>
>> Note the function used to convert ids to names.
> 
> Tried the following query:
> 
> SELECT conname AS name, pg_encoding_to_char( conforencoding ) AS
> encoding, condefault AS default FROM pg_conversion ORDER BY encoding;
> 
> and got following results (for simplicity I will post only couple of rows):
> 
>   big5_to_utf8                   | BIG5           | t
>   big5_to_euc_tw                 | BIG5           | t
>   big5_to_mic                    | BIG5           | t
>   euc_cn_to_mic                  | EUC_CN         | t
>   euc_cn_to_utf8                 | EUC_CN         | t
>   euc_jis_2004_to_shift_jis_2004 | EUC_JIS_2004   | t
>   euc_jis_2004_to_utf8           | EUC_JIS_2004   | t
>   euc_jp_to_mic                  | EUC_JP         | t
>   euc_jp_to_sjis                 | EUC_JP         | t
>   euc_jp_to_utf8                 | EUC_JP         | t
>   euc_kr_to_utf8                 | EUC_KR         | t
>   euc_kr_to_mic                  | EUC_KR         | t
>   euc_tw_to_big5                 | EUC_TW         | t
>   euc_tw_to_utf8                 | EUC_TW         | t
>   euc_tw_to_mic                  | EUC_TW         | t
> 
> What I noticed is that all encodings are default, as they all have 't'
> in the last column.
> 
> It's a little confusing...

Not if you read the docs:

https://www.postgresql.org/docs/current/catalog-pg-conversion.html

"The catalog pg_conversion describes encoding conversion functions. See 
CREATE CONVERSION for more information."

https://www.postgresql.org/docs/current/sql-createconversion.html

"Conversions that are marked DEFAULT can be used for automatic encoding 
conversion between client and server. To support that usage, two 
conversions, from encoding A to B and from encoding B to A, must be 
defined."


> 
> Thx for the help.
> 
>>
>>>
>>>
>>> Or is it hard coded inside the PostgreSQL codebase?
>>
>>
>>   Yes.  Doesn’t preclude exposing it via SQL but we don’t do so directly.
>>
>> David J.
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com