Re: check_locale() and the empty string

On Sat, 2012-03-24 at 19:07 -0400, Tom Lane wrote:
> Jeff Davis <pgsql@j-davis.com> writes:
> > Surely we don't want it to be set from the environment, right?
>
> Why not?

I agree that we shouldn't change the documented behavior of those GUCs.

But a SQL command like CREATE DATABASE being environment sensitive does
seem like surprising behavior to me, and it did indirectly
lead to a bug.

> I do agree that it's probably unwise to store an empty string as the
> value of pg_database.datcollate or datctype, because that would mean
> that if the server is restarted with different LC_XXX environment values
> then it will think the database has different locale settings, leading
> to havoc.

Yes, that's the worst of the problem. I should have mentioned that more
explicitly in the original report.

> However, ISTM the right fix is to replace an empty-string
> value with the implied locale name at createdb time.  Proposed patch
> attached.

+1.

> Note 2: there is code in initdb that is supposed to be kept parallel
> to this, but it's not currently making any attempt to canonicalize
> non-empty locale names.  Should we make it do that too?

I assume you are talking about the code that results in writing the
settings to postgresql.conf?

It doesn't look quite as dangerous in that area because (a) it ignores
zero-length strings; and (b) setting the GUC to the wrong value will
either be prevented or will not cause any major problem. However, it
does seem like a good idea to canonicalize the settings unless there is
some reason not to.

Regards,
    Jeff Davis