I have accidentally deleted the default "postgres" database from my postgres. I've read that:
Most Postgres servers have three databases defined by default: template0 , template1 and postgres . template0 and template1 are skeleton databases that are or can be used by the CREATE DATABASE command. postgres is the default database you will connect to before you have created any other databases.
I have now created again a postgres database by running CREATE DATABASE postgres.
Do I need to do anything else to basically redo deleting the "postgres" database? Or the current one is basically the same?
Thanks
The database postgres is in no way special. You should use the bootstrap superuser (normally postgres) as the database owner, then the database will be just as good as the original postgres database.
The only difference is that the new database will have an OID ≥ 16384, which identifies it as an object created after cluster initialization. However, a quick look through the source code makes me believe that we don't use that anywhere.
Related
I accidentally restored another database as the default postgres database, how do I correct this?
postgres v10 on ubuntu.
To be specific. Log into a database other then postgres.
Then:
DROP DATABASE postgres;
CREATE DATABASE postgres; --You don't need to specify template1 it is the default.
Then do your restore. If you are using pg_restore make sure you use -C to have the database CREATEd properly.
I have restored a snapshot from an existing RDS PostgreSQL database. Now I want to rename that database but can't find how to do it anywhere in the AWS documentation.
Nor can I find how to use the master password (which I expect let's me do it).
Logging in with postgres into template1 database and then ALTER DATABASE foo RENAME TO bar; worked
I've just set up Postgres for use by different users on my network. Every user has his own username/password/database, but when I connect to Pg I can also see a 'postgres' database (and even create tables etc). I tried to REVOKE access to that database from public but then it won't let me connect. What exactly is the postgres database and why is it needed? Can I disable it so that users only see the database(s) I've created for them?
The postgres database is created by default when you run initdb.
Quote from the manual:
Creating a database cluster consists of creating the directories in which the database data will live (...) creating the template1 and postgres databases. When you later create a new database, everything in the template1 database is copied. (...) The postgres database is a default database meant for use by users, utilities and third party applications.
There is nothing special about it, and if you don't need it, you can drop it:
drop database postgres;
You need to do that as a superuser of course. The only downside of this is that when you run psql as the postgres operating system user, you need to explicitly provide a database name to connect to
If you drop the postgres database you'll find a few things to be confusing. Most tools default to using it as the default database to connect to, for one thing. Also, anything run under the postgres user will by default expect to connect to the postgres database.
Rather than dropping it, REVOKE the default connect right to it.
REVOKE connect ON DATABASE postgres FROM public;
The superuser (usually postgres), and any users you explicitly grant rights to access the database can still use it as a convenience DB to connect to. But others can't.
To grant connect rights to a user, simply:
GRANT connect ON DATABASE postgres TO myuser;
I did not know that template0 and template1 database templates are required in order to create empty databases. I deleted them in order to clear up postgres. Now I'm not able to create any new database. Gives me this error :
ERROR: template database "template1" does not exist
What can I do to get things going once again. I'll be very thankful for any help.
Luckily I had postgres database preserved because it was required for the postgres user to log into psql. Thus, created a template0 and template1 database :
create database template0 TEMPLATE postgres;
and same for template1. Then executed :
update pg_database set datistemplate=true where datname='template0';
for both databases to stop myself from accidentally deleting these templates again.
Everything works fine now :)
On my CentOS 7 box, I was not so lucky as to still have a database to connect to. However:
su postgres -c "initdb /var/lib/pgsql/data"
(as root) created a template0 and template 1 to work with.
For postgres 12.3 the following worked for me.
I deleted template1 not knowing what it was. I was able to create it from template0. You could also create it from postgres.
createdb -T template0 template1
createdb -T postgres template1
This is suggested in the docs -
template1 and template0 do not have any special status beyond the fact that the name template1 is the default source database name for CREATE DATABASE. For example, one could drop template1 and recreate it from template0 without any ill effects.
https://www.postgresql.org/docs/current/manage-ag-templatedbs.html
on my debian machine, i upgraded some clusters to version 11.
the template[01] databases on the target cluster have been dropped, rendering me with the ones from the older versions.
as root, i created a new cluster with pg_createcluster.
as user postgres:
dump the databases of the new cluster with pg_dumpall (with the --clean flag).
drop the new cluster.
import the resulted source in your cluster with psql.
i would remove the drop role postgres and creation of the same.
best regards,
alex
What are the default databases in PostgreSQL at the time of installation?
template1: the "default" database, which is copied when you perform "create database foo"
template0: the "minimal default" database, which serves essentially the same purpose, but typically used to create databases when restoring dumps which might already have the extra objects that are in template1, or to create a database that uses a different character encoding to the server default (template0 should only contain ASCII characters in strings)
postgres: an "administrative" database, which clients can assume exists to connect to merely to list which databases are available etc. Also, for example, pgAdmin will install the pg_agent schema in this database.
Apparently there is a database "postgres" that is created by default on each postgresql server installation.
It appears that it does not really have a well-defined purpose. According to the docs:
Creating a database cluster consists of creating the directories in
which the database data will live, generating the shared catalog
tables (tables that belong to the whole cluster rather than to any
particular database), and creating the template1 and postgres
databases. When you later create a new database, everything in the
template1 database is copied. (Therefore, anything installed in
template1 is automatically copied into each database created later.)
The postgres database is a default database meant for use by users,
utilities and third party applications.
(Source: http://www.postgresql.org/docs/8.2/static/app-initdb.html )