Kill a postgresql session/connection

Question

How can I kill all my postgresql connections?

I\'m trying a rake db:drop but I get:

ERROR:  database \"database_name\" is being accessed         


        

Answer 1

You can use pg_terminate_backend() to kill a connection. You have to be superuser to use this function. This works on all operating systems the same.

SELECT 
    pg_terminate_backend(pid) 
FROM 
    pg_stat_activity 
WHERE 
    -- don't kill my own connection!
    pid <> pg_backend_pid()
    -- don't kill the connections to other databases
    AND datname = 'database_name'
    ;

Before executing this query, you have to REVOKE the CONNECT privileges to avoid new connections:

REVOKE CONNECT ON DATABASE dbname FROM PUBLIC, username;

If you're using Postgres 8.4-9.1 use procpid instead of pid

SELECT 
    pg_terminate_backend(procpid) 
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 = 'database_name'
    ;

Answer 2

Easier and more updated way is:

1. Use ps -ef | grep postgres to find the connection #
2. sudo kill -9 "#" of the connection

Note: There may be identical PID. Killing one kills all.

Answer 3

For me worked the following:

sudo gitlab-ctl stop
sudo gitlab-ctl start gitaly
sudo gitlab-rake gitlab:setup [type yes and let it finish]
sudo gitlab-ctl start

I am using:
gitlab_edition: "gitlab-ce"
gitlab_version: '12.4.0-ce.0.el7'

Answer 4

In PG admin you can disconnect your server (right click on the server) & all sessions will be disconnected at restart

Answer 5

There is no need to drop it. Just delete and recreate the public schema. In most cases this have exactly the same effect.

namespace :db do

desc 'Clear the database'
task :clear_db => :environment do |t,args|
  ActiveRecord::Base.establish_connection
  ActiveRecord::Base.connection.tables.each do |table|
    next if table == 'schema_migrations'
    ActiveRecord::Base.connection.execute("TRUNCATE #{table}")
  end
end

desc 'Delete all tables (but not the database)'
task :drop_schema => :environment do |t,args|
  ActiveRecord::Base.establish_connection
  ActiveRecord::Base.connection.execute("DROP SCHEMA public CASCADE")
  ActiveRecord::Base.connection.execute("CREATE SCHEMA public")
  ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO postgres")
  ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO public")
  ActiveRecord::Base.connection.execute("COMMENT ON SCHEMA public IS 'standard public schema'")
end

desc 'Recreate the database and seed'
task :redo_db => :environment do |t,args|
  # Executes the dependencies, but only once
  Rake::Task["db:drop_schema"].invoke
  Rake::Task["db:migrate"].invoke
  Rake::Task["db:migrate:status"].invoke 
  Rake::Task["db:structure:dump"].invoke
  Rake::Task["db:seed"].invoke
end

end

Answer 6

Just wanted to point out that Haris's Answer might not work if some other background process is using the database, in my case it was delayed jobs, I did:

script/delayed_job stop

And only then I was able to drop/reset the database.