Re: Why format() adds double quote?

> 2016-01-24 8:04 GMT-02:00 Tatsuo Ishii <ishii(at)postgresql(dot)org>:
>>> On Wed, Jan 20, 2016 at 4:20 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>>>> If we would go this way, question is if we should back patch this or
>>>>> not since the patch apparently changes the existing
>>>>> behaviors. Comments? I would think we should not.
>>>>
>>>> I am sure, so we should not backport this change. This can breaks customer
>>>> regress tests - and the current behave isn't 100% correct, but it is safe.
>>>
>>> Quite. This is not a bug fix. It's a behavior change, perhaps for the better.
>>
>> Added to the commitfest 2016-03.
>
> Hi,
>
> I gone ahead a little and tested this patch and it works like was
> proposed, I agree that it's not a bug fix but a new behavior so -1 for
> backport.

IMO, it's a bug or at least an inconsistency but I admit it's too late
to back patch to existing stable branches.

> While applying patch against master
> (1129c2b0ad2732f301f696ae2cf98fb063a4c1f8) it offsets two hunks.
>
> Since format() has regression tests I suggest that one should be added
> to cover this.

I don't think it's doable. The test requires to handle multiple
database encodings. The regression test framework handles only one
database encoding. Probably adding to the existing mb test is the
easiest.

> It could worth to add the new behavior to the docs,
> since there no explicit example for %I.

> I performed the follow tests that works as expected using some Portuguese words:

I assume you used UTF-8 encoding database.
Great.

> postgres=# create table test (nome varchar, endereço text, "UF"
> varchar(2), título varchar);
> CREATE TABLE
> Time: 80,769 ms
> postgres=# select format('%I', attname) from pg_attribute join
> pg_class on (attrelid = oid) where relname = 'test';
> format
> ----------
> "UF"
> cmax
> cmin
> ctid
> endereço
> nome
> tableoid
> título
> xmax
> xmin
> (10 rows)
>
> Time: 1,728 ms
> postgres=# select format('%I', 'endereco');
> format
> ----------
> endereco
> (1 row)
>
> Time: 0,098 ms
> postgres=# select format('%I', 'endereço');
> format
> ----------
> endereço
> (1 row)
>
> Time: 0,088 ms
> postgres=# select format('%I', 'あああ');
> format
> --------
> あああ
> (1 row)
>
> Time: 0,072 ms
> postgres=# select format('%I', 'título');
> format
> --------
> título
> (1 row)
>
> Time: 0,051 ms
> postgres=# select format('%I', 'título e');
> format
> ------------
> "título e"
> (1 row)
>
> Time: 0,051 ms
> postgres=# select format('%I', 'título_e');
> format
> ----------
> título_e
> (1 row)
>
> Time: 0,051 ms
> postgres=# select format('%I', '_título');
> format
> ---------
> _título
> (1 row)
>
> Time: 0,047 ms
> postgres=# select format('%I', '1_título');
> format
> ------------
> "1_título"
> (1 row)
>
> Time: 0,046 ms
>
>
> Thank you for this!
>
>
> Best regards,
> --
> Dickson S. Guedes
> mail/xmpp: guedes(at)guedesoft(dot)net - skype: guediz
> http://github.com/guedes - http://guedesoft.net
> http://www.postgresql.org.br