Trying to rename a database in Redshift cluster - amazon-redshift

I'm trying to rename a database in my Redshift cluster.
You cannot rename the database when you're connected to it so I've created a temporary database, reconnected with SQL Workbench to the temporary db and issued:
ALTER DATABASE olddb RENAME to newdb;
I get an error stating ERROR: database "olddb" is being accessed by other users [SQL State=55006]
I've checked who is connected and there appear to be some connections from user rdsdb to the database. I assume this is a service account that AWS Redshift use to perform maintenance tasks etc.
How can I rename the database when this superuser is connected?
Many thanks.

You cannot alter the name of (or delete!) the database that is created during the initial cluster creation. I don't believe this is mentioned in the docs but I've confirmed it with them.

We can change the database name which is already created.
Detailed steps on how to do
Connect to the old database and create a new database if you do not have another one already.
create database databasebasename
In this example, I will call the databasename as 'newdb'.
Connect to newdb using connecting string as, jdbc:redshift://.us-east-1.redshift.amazonaws.com:8192/newdb, with the same password and username of your superuser (or the other eligible users as mentioned above).
Now you can alter the database name. Substitute 'database_name_new' with the desired databasename.
alter database old-db-name rename to database_name_new;
If there are any active sessions, you'll have to kill them. To find the pid of active sessions:
select * from STV_SESSIONS where user_name='rdsdb';
Then to kill a session:
SELECT
pg_terminate_backend(<pid>)
FROM
pg_stat_activity
WHERE
-- don't kill my own connection!
procpid <> pg_backend_pid()
-- don't kill the connections to other databases
AND datname = '<old-db-name>';
Once complete, you can connect back to that new database using the new name in the connection string as
jdbc:redshift://<cluser-id>.us-east-1.redshift.amazonaws.com:8192/database_name_new
You can delete the temporary 'newdb'.
drop database databasebasename

That's possible now -- I just renamed the database that was created during the initial cluster creation.

We had a similar situation.
Step 1: Connect to the database which is not the one you are trying to rename. Check the same by executing SELECT CURRENT_DATABASE();.
Step 2: Execute the query below -
SELECT
ss.*, 'select pg_terminate_backend('||process||');'
FROM
stv_sessions ss
ORDER BY
db_name;
The output of the query will have a column at the end with the select statements. Execute those to kill the sessions.
Step 3(Optional): If you are not the owner of the database try to modify the ownership of the database -
ALTER DATABASE <database to be renamed>
OWNER TO <user which is going to do the rename>;
Step 4: Rename the database

Related

How to DROP tables from specific database-schema in Postgresql?

I am new to Postgresql and so far I have not found a way to drop a table from specific database. To give some context:
We are doing a synchronization from Oracle to PostgreSQL of 5 tables. In postgres I have a database SoloCopy and the schema is the default public. In the Postgresql instance we have also 2 more databases SoloSynch and postgres (the default one).
What I want to do is to select SoloCopy database and:
DROP TABLE public.table1;
When I do the above DROP statement table1 is deleted only from the database that was selected when opening SQL Query. But I want to specify the database before that and to be irrelevant from where the SQL Query was open. How can I do that?
I found an answer on my own. Setup can be found here:
Psql in Task Scheduler does not run a file script
Basically I needed to use PSQL and with the connection string there I connect to a specific DB, which I can drop the tables from. The details for PGPASSWORD and the .bat file I ended up creating are in the link above. Had to start everything from CMD and switch to psql from there.

PostgreSQL 13: create empty copy of database

I have a AWS RDS PostgreSQL 13 server with some databases. I have to create an empty copy of one database (empty means schema (tables, views, functions) + security (users, roles)).
Is pg_dump -s what I am looking for?
Thanks!
pg_dump -d db_name -s. You will also need to do pg_dumpall -g to get the global data e.g. roles. This will get all global data for the Postgres cluster, so you may have more then you need for the particular database.
Postgres allows the use of any existing database on the server as a template when creating a new database. I'm not sure whether pgAdmin gives you the option on the create database dialog but you should be able to execute the following in a query window if it doesn't:
CREATE DATABASE newdb WITH TEMPLATE originaldb OWNER dbuser;
Still, you may get:
ERROR: source database "originaldb" is being accessed by other users
To disconnect all other users from the database, you can use this query:
SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE pg_stat_activity.datname = 'originaldb' AND pid <> pg_backend_pid();

Create Postgres User with admin rights just for one database

How can I create a postgres user who has admin access only to one database but cannot inspect or interfere with other databases in the postgres instance? The use case is I'm creating a multitenant application
where each tenant gets his own database in the postgresql instance and can create schemas, tables etc and
perhaps use a few pg_tables to inspect his own database but not others.
cannot change the name of the database as it's controlled by me
EDIT: Added more constraints
That's fairly trivial:
CREATE DATABASE newdb;
GRANT CREATE ON DATABASE newdb TO newdba;
Add pg_hba.conf entries to allow newdba to connect to newdb only.

How to shut down one database in a db2 instance?

I want to shut down one database in a db2 instance with multiple dbs.
I don't want to deactivate the db as it will reconnect when I try to connect. It should be completely shut down so I get a connection error when trying to connect to the db.
This is not a programming question so it can be viewed as off topic.
There are different techniques, each has advantages/disadvantages.
You can quiesce the database and later unquiesce it.
or you can revoke connect rights, and later grant them, but this depends on how well your role separation is done.
or you force off existing applications and then connect in exclusive mode as the instance owner (provided that your applications NEVER connect with instance-owner credentials).
One trick you could use is to temporarily recatalog the database you want to deactivate under a different name; this will prevent applications from connecting to it using the original name, regardless of the authority they use.
First, determine the database path by looking at its catalog entry:
db2 list db directory
The value of the "Local database directory" property is what you need.
Now you can recatalog the database:
db2 uncatalog db orig_db
db2 catalog db orig_db as foobar on <path>
where <path> is the local database directory determined previously.
Once you force all applications currently connected to the database in question you will be able to deactivate the database:
db2 list applications
db2 "force application (<app id 1>, <app id 2>,...)
db2 deactivate db foobar
Later on you can restore the catalog entry to its original value:
db2 uncatalog db foobar
db2 catalog db orig_db on <path>

Postgres drop database error: pq: cannot drop the currently open database

I'm trying to drop the database I'm currently connected to like so, but I'm getting this error:
pq: cannot drop the currently open database
I don't really understand how I'm expected to drop the database if I have to close my connection, because then I don't think I will be able to use dbConn.Exec to execute my DROP DATABASE statement?
dbConn *sql.DB
func stuff() error {
_, err := dbConn.Exec(fmt.Sprintf(`DROP DATABASE %s;`, dbName))
if err != nil {
return err
}
return dbConn.Close()
}
I guess I could connect to a different database and then execute it on that connection, but I'm not even sure if that'd work, and it seems really weird to have to connect to a new database just to drop a different database. Any ideas? Thanks.
Because, you are trying to execute dropDb command on database, to which you have open connection.
According to postgres documentation:
You cannot be connected to the database you are about to remove. Instead, connect to template1 or any other database and run this command again.
This makes sense, because when you drop the entire database, all the open connection referencing to that database becomes invalid, So the recommended approach is to connect to different database, and execute this command again.
If you are facing a situation, where a different client is connected to the database, and you really want to drop the database, you can forcibly disconnect all the client from that particular database.
For example, to forcibly disconnect all clients from database mydb:
If PostgreSQL < 9.2
SELECT pg_terminate_backend(procpid) FROM pg_stat_activity WHERE datname = 'mydb';
Else
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = 'mydb';
Note: This command requires superuser privileges.
Then, you can connect to different database, and run dropDb command again.
If you encounter this problem in IntelliJ, change the schema with the following dropdown to postgres.
After that, I was able to drop a db.
I am using PostgreSQL 12 and pgAdmin-4 in Windows 10. I had to use a combination of the above answers to drop a database, which I could not drop in pgAdmin because I was unable to close all open connections in pgAdmin.
Close pgAdmin-4.
In Windows command line, assuming my server's name is postgres and my database is mydb:
C:\> psql -U postgres
I logged in with my server password.
I then closed all open connections to mydb:
postgres-# SELECT * FROM pg_stat_activity WHERE pg_stat_activity.datname='mydb';
postgres-# SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = 'mydb';
Finally, I successfully dropped mydb:
postgres-# DROP DATABASE mydb;
Now if I go back into pgAdmin-4 it is gone.
To drop the database:
\c postgres
Then
DROP DATABASE your_database works
It's simple, just connect to another database \c database2. Once connected execute the drop database command while connected to the other database.
Just Connect to a different database using \c db_name;
and then drop the required database using drop database db_name;
If you are using DBeaver make sure you are not connected to the database you are trying to drop. Go to edit connections and look at the database name.
Switch the connection to a different database and then drop the database you wish.
None of this worked for me since I tried to do it through pgAdmin which kept database connections open as soon as I delete them.
Solution:
C:\Program Files\PostgreSQL\11\scripts\runpsql.bat
after you supply correct information you will be able to get pg command prompt, here you can just type:
dbdrop yourdatabase
After that you might still see database in pgAdmin but now you can just simply delete it with right click and DELETE/DROP option.
you can force to drop database with: DROP DATABASE mydb WITH (FORCE)