Thread: BUG #13702: pg_dump interprets “=” in a db name incorrectly

The following bug has been logged on the website:

Bug reference:      13702
Logged by:          Felipe Gasper
Email address:      felipe@felipegasper.com
PostgreSQL version: Unsupported/Unknown
Operating system:   Linux
Description:

For the purposes of an administrative frontend that I help develop/maintain,
I have a database named:

--------------
abcde_1234567890-=~!@#$%^&*()_+[]\{}|;:?,.<b><b> spaces
--------------

When I try to back up this DB via pg_dump, the utility appears to split the
DB name on the “=”, thinking that it’s another command-line option.

I’ve tried passing in “--”, but no joy. I tried passing “--dbname” then the
DB name, but pg_dump doesn’t seem to accept that argument.

The only working solution I have found is to set the DB name in PGDATABASE.

I found this in 9.0.18. Maybe it’s still a problem in supported releases,
too?

On 22 Oct 2015 7:56 PM, David G. Johnston wrote:
> On Thu, Oct 22, 2015 at 8:34 PM, <felipe@felipegasper.com
> <mailto:felipe@felipegasper.com>>wrote:
>
>     The following bug has been logged on the website:
>
>     Bug reference:      13702
>     Logged by:          Felipe Gasper
>     Email address: felipe@felipegasper.com <mailto:felipe@felipegasper.com>
>     PostgreSQL version: Unsupported/Unknown
>     Operating system:   Linux
>     Description:
>
>     For the purposes of an administrative frontend that I help
>     develop/maintain,
>     I have a database named:
>
>     --------------
>     abcde_1234567890-=~!@#$%^&*()_+[]\{}|;:?,.<b><b> spaces
>     --------------
>
>     When I try to back up this DB via pg_dump, the utility appears to
>     split the
>     DB name on the “=”, thinking that it’s another command-line option.
>
>     I’ve tried passing in “--”, but no joy. I tried passing “--dbname”
>     then the
>     DB name, but pg_dump doesn’t seem to accept that argument.
>
>
> "--dbname=..." ​Documented 9.3 and above​
>
>
>     The only working solution I have found is to set the DB name in
>     PGDATABASE.
>
>     I found this in 9.0.18. Maybe it’s still a problem in supported
>     releases,
>     too?
>
>
> It was decided to make the database name in this situation be an
> abstract concept as opposed to strictly referring to a named database.
> Because of this the equal sign has a special meaning that, apparently,
> cannot be overridden.
>
> You may want to consider URI format - the following appears to work (9.3
> tested)
>
> psql postgres:///db=123
>  >psql: FATAL: database "db=123" does not exist
>

Interesting -- also, in 9.0 I *can* do:

dbname='...'

… and it works. Undocumented, apparently (?), but it does the job.

But, I actually have to support all the way back to 8.1, and I’m a bit
leery of relying on undocumented (?) features for our backup
functionality. Hopefully down the road we can just move everything to
 >=9.3, and peace and love will reign. :)

Thank you!

-Felipe Gasper
Houston, TX

On Thu, 22 Oct 2015 20:30:20 -0500
Felipe Gasper <felipe@felipegasper.com> wrote:

> Interesting -- also, in 9.0 I *can* do:
>
> dbname='...'
>
> … and it works. Undocumented, apparently (?), but it does the job.
>
> But, I actually have to support all the way back to 8.1, and I’m a bit
> leery of relying on undocumented (?) features for our backup
> functionality. Hopefully down the road we can just move everything to
>  >=9.3, and peace and love will reign. :)

You can dump and load older version database from newer version clients.
The dbname parsing problem you are having is on the client, not the server,
so if you can arrange to take the backup with a more current client then
one of the suggestions in this thread will work for you.

-dg

--
David Gould                                   daveg@sonic.net
If simplicity worked, the world would be overrun with insects.

Apparently 9.0 can’t pg_restore DBs that have equals signs in them...at
least, such is the case with pg_restore on 9.0.18. It gets confused by
the “=”, even when it’s in the --dbname argument.

To me, that seems like a bug, as there’s no reason that the --dbname
argument should be interpreted as anything other than the name of a
database.

Does anyone here happen to know when pg_restore offered alternative ways
of specifying the database?

-FG

On 23 Oct 2015 7:45 AM, David Gould wrote:
> On Thu, 22 Oct 2015 20:30:20 -0500
> Felipe Gasper <felipe@felipegasper.com> wrote:
>
>> Interesting -- also, in 9.0 I *can* do:
>>
>> dbname='...'
>>
>> … and it works. Undocumented, apparently (?), but it does the job.
>>
>> But, I actually have to support all the way back to 8.1, and I’m a bit
>> leery of relying on undocumented (?) features for our backup
>> functionality. Hopefully down the road we can just move everything to
>>   >=9.3, and peace and love will reign. :)
>
> You can dump and load older version database from newer version clients.
> The dbname parsing problem you are having is on the client, not the server,
> so if you can arrange to take the backup with a more current client then
> one of the suggestions in this thread will work for you.
>
> -dg
>

On 23 Oct 2015 1:33 PM, David G. Johnston wrote:
> On Fri, Oct 23, 2015 at 2:20 PM, Felipe Gasper <felipe@felipegasper.com
> <mailto:felipe@felipegasper.com>>wrote:
>
>     Apparently 9.0 can’t pg_restore DBs that have equals signs in
>     them...at least, such is the case with pg_restore on 9.0.18. It gets
>     confused by the “=”, even when it’s in the --dbname argument.
>
>     To me, that seems like a bug, as there’s no reason that the --dbname
>     argument should be interpreted as anything other than the name of a
>     database.
>
>     Does anyone here happen to know when pg_restore offered alternative
>     ways of specifying the database?
>
>     -FG
>
>     On 23 Oct 2015 7:45 AM, David Gould wrote:
>
>         On Thu, 22 Oct 2015 20:30:20 -0500
>         Felipe Gasper <felipe@felipegasper.com
>         <mailto:felipe@felipegasper.com>> wrote:
>
>             Interesting -- also, in 9.0 I *can* do:
>
>             dbname='...'
>
>             … and it works. Undocumented, apparently (?), but it does
>             the job.
>
>             But, I actually have to support all the way back to 8.1, and
>             I’m a bit
>             leery of relying on undocumented (?) features for our backup
>             functionality. Hopefully down the road we can just move
>             everything to
>                >=9.3, and peace and love will reign. :)
>
>
>         You can dump and load older version database from newer version
>         clients.
>         The dbname parsing problem you are having is on the client, not
>         the server,
>         so if you can arrange to take the backup with a more current
>         client then
>         one of the suggestions in this thread will work for you.
>
>
> ​It would help greatly if you post full command lines and error messages...

Sorry; I hope the following is more helpful.

>
> Again, the "--dbname" argument can either be an actual database name or
> a "connection info" object.

But the documentation doesn’t say that; it only says that it’s the name
of the database. Should the documentation be updated, then?

>  In the later case the "=" has a special
> meaning.  If your database has an "=" in its name then it seems like you
> have to use the "connection info" definition form.  Note I haven't dug
> into this with respect to pg_restore but that is the findings from the
> brief psql test I performed.

Is “connection info” an option with pg_restore, though, which mandates a
--dbname argument?

Here is the execve from strace:

------------
[pid 21172] execve("/usr/local/pgsql/bin/pg_restore",
["/usr/local/pgsql/bin/pg_restore", "--username=postgres",
"--host=/tmp/TMP.work.mVasksDJkt0CEJJh/socket", "--no-privileges",
"--no-owner", "-d", "weird  alpha_0123~-_=+[{]}\\\\;:,<.>?",
"--single-transaction", "--role", "weird
alpha_0123~-_=+[{]}\\\\;:,<.>?"], [/* 8 vars */]) = 0
------------

It spits out the following on STDERR:

-------------
[archiver (db)] connection to database "" failed: missing "=" after
"weird" in connection info string
-------------

It makes sense that the “=” would be interpreted as a special character
in pg_dump when there is no --dbname parameter. But the docs say that
--dbname is for a database name; there is no mention of any kind of
parsing otherwise. Should it not work that way? What purpose is served
by passing configuration parameters in the database name?

This does work with 9.4 when I use the “postgres:///…” syntax; however,
as we’re stuck supporting older PgSQLs for the time being (*sigh* even
back to 8.1), and as PGDATABASE doesn’t work with pg_restore, are we
left with having to prohibit “=” in database names?

-FG

On 23 Oct 2015 2:14 PM, David G. Johnston wrote:
> On Fri, Oct 23, 2015 at 2:54 PM, Felipe Gasper <felipe@felipegasper.com
> <mailto:felipe@felipegasper.com>>wrote:
>
>     On 23 Oct 2015 1:33 PM, David G. Johnston wrote:
>
>         On Fri, Oct 23, 2015 at 2:20 PM, Felipe Gasper
>         <felipe@felipegasper.com <mailto:felipe@felipegasper.com>
>         <mailto:felipe@felipegasper.com
>         <mailto:felipe@felipegasper.com>>>wrote:
>
>
>
>         Again, the "--dbname" argument can either be an actual database
>         name or
>         a "connection info" object.
>
>
>     But the documentation doesn’t say that; it only says that it’s the
>     name of the database. Should the documentation be updated, then?
>
>           In the later case the "=" has a special
>         meaning.  If your database has an "=" in its name then it seems
>         like you
>         have to use the "connection info" definition form.  Note I
>         haven't dug
>         into this with respect to pg_restore but that is the findings
>         from the
>         brief psql test I performed.
>
>
>     Is “connection info” an option with pg_restore, though, which
>     mandates a --dbname argument?
>
>
> ​
> http://www.postgresql.org/docs/9.4/interactive/libpq-connect.html#LIBPQ-CONNECT-DBNAME
> ​
> dbname
> The database name. Defaults to be the same as the user name. In certain
> contexts, the value is checked for extended formats; see Section 31.1.1
> for more details on those.
>
> ​31.1.1
> http://www.postgresql.org/docs/9.4/interactive/libpq-connect.html#LIBPQ-CONNSTRING
> ​
> ​See "dbname" in particular
>
> So it is documented.​  Suggestions and patches welcomed if you think it
> should be covered differently.

Ah, ok.

The reason why I didn’t find this myself was that there’s nothing that
leads me from the pg_restore docs’ description of the --dbname parameter
to the sections you’ve mentioned above.

Maybe that’s the thing, then--would it work to add a link to describe
how pg_restore parses the argument to “--dbname”? A usage example, too,
perhaps, to show how any valid DB name that the PostgreSQL server
recognizes can be fed into pg_restore, pg_dump, etc.?

>
> ​pg_restore --dbname="dbname=crazy=db=name" [...] likely will work but I
> cannot quickly test it ATM.
>

Hooray! At least in 9.0.18, if I quote the DB name as conninfo string, I
can indeed restore to a DB with spaces, equals, etc. in its name.

Now to try it in 8.1. If it doesn’t work there, we’ll probably just
forbid “=” in DB names and call it a day.

Thank you for your responses. I hope I’ve not been untoward in any of this

-FG