Postgresql – Why isn’t pg_restore –create working

pg-dumppg-restorepostgresqlpostgresql-9.4

I backed up a database called app_data, on a 9.3 server, with this basic command:

pg_dump -n public -F custom app_data > app_data.pg.dump

Then I try to restore it on another server (running 9.4) like this:

pg_restore -C -d postgres app_data.pg.dump

But it puts all the tables in the postgres database. The man page says it will create and use a new database, app_data.

-C –create

Create the database before restoring into it. […]

When this option is used, the database named with -d is used only to issue the initial DROP DATABASE and CREATE DATABASE commands. All data is
restored into the database name that appears in the archive.

That's not what it's doing. The name in the archive is app_data:

bash-4.2$ pg_restore -l app_data.pg.dump 
;
; Archive created at Tue Dec 15 04:16:52 2015
;     dbname: app_data
...

Am I doing something wrong?

Best Answer

Yes that behaviour is something that I should report to postgres as use of different flags doesnt seem to have an effect and it just doesnt work. To solve it use:

create DB

createdb -h HOST -U USER -W DB_NAME

restore and in case of Error Stop

egrep -v 'EXTENSION.*plpgsql' DUMPFILE.sql | psql -h HOST -U USER -W -d DB_NAME -v ON_ERROR_STOP=1

Related Solutions

Postgresql – How to make pg_dump skip extension

For anyone looking for a workaround, limiting pg_restore to a specific schema has helped me get around this bug. See https://stackoverflow.com/a/11776053/11819

PostgreSQL – pg_restore Error: Schema ‘public’ Already Exists

The error is harmless but to get rid of it, I think you need to break this restore into two commands, as in:

dropdb -U postgres mydb && \
 pg_restore --create --dbname=postgres --username=postgres pg_backup.dump

The --clean option in pg_restore doesn't look like much but actually raises non-trivial problems.

For versions up to 9.1

The combination of --create and --clean in pg_restore options used to be an error in older PG versions (up to 9.1). There is indeed some contradiction between (quoting the 9.1 manpage):

--clean Clean (drop) database objects before recreating them

and

--create Create the database before restoring into it.

Because what's the point of cleaning inside a brand-new database?

Starting from version 9.2

The combination is now accepted and the doc says this (quoting the 9.3 manpage):

--clean Clean (drop) database objects before recreating them. (This might generate some harmless error messages, if any objects were not present in the destination database.)

--create Create the database before restoring into it. If --clean is also specified, drop and recreate the target database before connecting to it.

Now having both together leads to this kind of sequence during your restore:

DROP DATABASE mydb;
...
CREATE DATABASE mydb WITH TEMPLATE = template0... [other options]
...
CREATE SCHEMA public;
...
CREATE TABLE...

There is no DROP for each individual object, only a DROP DATABASE at the beginning. If not using --create this would be the opposite.

Anyway this sequence raises the error of public schema already existing because creating mydb from template0 has imported it already (which is normal, it's the point of a template database).

I'm not sure why this case is not handled automatically by pg_restore. Maybe this would cause undesirable side-effects when an admin decides to customize template0 and/or change the purpose of public, even if we're not supposed to do that.

Best Answer

Related Solutions

Postgresql – How to make pg_dump skip extension

PostgreSQL – pg_restore Error: Schema ‘public’ Already Exists

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