Mention invalid null byte sequence

On Sat, 2020-12-05 at 21:58 +0000, PG Doc comments form wrote:

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/datatype-character.html
Description:

I discovered accidentally that PostgreSQL doesn't accept null byte in text
type. It seems that Oracle does (see
/messages/by-id/de752e01-f36c-821e-9181-cfba78c0fbc8@propaas.com)
and SQLite does it too.

So it should written in the character type that null byte are not accepted,
it would make like easier to migrate to PostgreSQL :)

+1; how about the attached patch?

Yours,
Laurenz Albe

Le 07/12/2020 à 10:02, Laurenz Albe a écrit :

On Sat, 2020-12-05 at 21:58 +0000, PG Doc comments form wrote:

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/datatype-character.html
Description:

I discovered accidentally that PostgreSQL doesn't accept null byte in text
type. It seems that Oracle does (see
/messages/by-id/de752e01-f36c-821e-9181-cfba78c0fbc8@propaas.com)
and SQLite does it too.

So it should written in the character type that null byte are not accepted,
it would make like easier to migrate to PostgreSQL :)

+1; how about the attached patch?

That would be a good start indeed.

I don't know the policy for documentation redundancy in PostgreSQL, but
it should be good to mention that also in
https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE
since the basic "SELECT E'la\x00la';" will fail while "SELECT
E'la\x01la';" will not.

And, as a lazy person, I also would like to see it in the general
datatype page, since it's a common behavior.

Anyway, merging the first patch will enable the search for "NUL
character" to return a result, and that will be definitively a nice
improvement!

Have a nice day!

Adrien

Laurenz Albe <laurenz.albe@cybertec.at> writes:

On Sat, 2020-12-05 at 21:58 +0000, PG Doc comments form wrote:

The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/13/datatype-character.html
Description:

So it should written in the character type that null byte are not accepted,
it would make like easier to migrate to PostgreSQL :)

+1; how about the attached patch?

I had thought that this was already documented, but after digging around
I can only find it mentioned in the contexts of saying that literal
strings and quoted identifiers can't contain \0. So yeah, we need to
improve that.

I agree with the submitter that the place one would expect to read about
this is in datatype-character.html. So I'd propose the attached.
Maybe there's reason to repeat the info in charset.sgml, but it seems
like more of a datatype limitation than a character set issue.

regards, tom lane

On Mon, 2020-12-07 at 15:27 -0500, Tom Lane wrote:

Laurenz Albe <laurenz.albe@cybertec.at> writes:

On Sat, 2020-12-05 at 21:58 +0000, PG Doc comments form wrote:

The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/13/datatype-character.html
Description:

So it should written in the character type that null byte are not accepted,
it would make like easier to migrate to PostgreSQL :)

+1; how about the attached patch?

I had thought that this was already documented, but after digging around
I can only find it mentioned in the contexts of saying that literal
strings and quoted identifiers can't contain \0. So yeah, we need to
improve that.

I agree with the submitter that the place one would expect to read about
this is in datatype-character.html. So I'd propose the attached.
Maybe there's reason to repeat the info in charset.sgml, but it seems
like more of a datatype limitation than a character set issue.

+1 on your patch.

Yours,
Laurenz Albe

Laurenz Albe <laurenz.albe@cybertec.at> writes:

On Mon, 2020-12-07 at 15:27 -0500, Tom Lane wrote:

I agree with the submitter that the place one would expect to read about
this is in datatype-character.html. So I'd propose the attached.
Maybe there's reason to repeat the info in charset.sgml, but it seems
like more of a datatype limitation than a character set issue.

+1 on your patch.

Pushed, thanks for looking it over.

regards, tom lane