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.
The file extension means nothing. At all. It's just a part of a file name.
If you want a custom-format dump for use with pg_restore
use -Fc
as an argument to pg_dump
.
pg_dump
defaults to generating SQL-format dumps for use with psql
.
See the manual for more details.
Best Answer
There are few command line options you need to consider.
-Fc
: restore from a binary back up as its more flexible than plain text SQL dump--dbname
: restore under this database name (must be created beforehand usingcreatedb
)-x
: do not try to restore access priviledges (e.g. the superuser name may change between databases)--no-owner
: the database owner user is different on the system where restore is performed--exit-on-error
: If bad stuff happens, abort and don't flood your terminal with useless errors