I had shared one article about, how to kill all running connections of PostgreSQL Database.

PostgreSQL: Script to Kill all Running Connections and Sessions of a Database

In this post, I am sharing small, but a very important note on PostgreSQL pg_terminate_backend and pg_cancel_backend which are used to kill the running query or session.

pg_cancel_backend():

It cancels the only running query. You can get the list of long running queries (pid) using pg_stat_activity.

If you want to kill any of those long running queries, you must use pg_cancel_backend() to kill it. You can cancel one query without destroying the connection, stopping the other queries.

pg_terminate_backend():

It terminates the entire process and database connection. It destroys everything for that particular role or user.

If you are very serious about to terminate the session without cancelling it, you can use this function otherwise you should avoid the use of this function.

The best practice is:

First find long running queries and their process ids (pid), cancel those queries using pg_cancel_backend and if it is not releasing, you should use pg_terminate_backend.

In this post, I am sharing scripts to kill all your running processes or sessions of SQL Server.

DBA always set time of database maintenance activities, but sometimes they find few running sessions so they require closing all connections of a SQL Server Database.

Before executing this script, please take care and verify all running connections and processes otherwise this script will harm to your data.

You require this type of script very occasionally, but I am sharing here because this is also one of the important scripts for SQL DBA.

How to find running sessions or processes in SQL Server?

Script to find Running Process and Session in SQL Server

Command to Kill particular session_id:

KILL 'session_id'

Script to kill multiple sessions:

DECLARE @DatabaseName nvarchar(50)
SET @DatabaseName = 'dbrnd'

DECLARE @SQL varchar(max)
SET @SQL = ''

SELECT @SQL = @SQL + 'Kill ' + Convert(varchar, SPId) + ';'
FROM MASTER..SysProcesses
WHERE DBId = DB_ID(@DatabaseName) AND SPId <> @@SPId

EXEC(@SQL)

Change your database mode from multi-user to single-user:

Once you change the database mode from multi-user to single-user, SQL Server immediately stops all the connections of the database. No one can connect to that database.

The DBA can perform the maintenance activity and after that, they can again change the database mode from single-user to multi-user.

To set Single User:

ALTER DATABASE [Database_Name] SET SINGLE_USER WITH ROLLBACK IMMEDIATE

To set Multi User:

ALTER DATABASE [Database_Name] SET MULTI_USER WITH ROLLBACK IMMEDIATE

In this post, I am sharing a script to kill all running connections and sessions of a PostgreSQL Database.

I need this script during the PostgreSQL maintenance task, in which we require to close all connections and sessions.

Before executing this script, please take care and verify all running connections and processes otherwise this script will harm to your data or transactions.

You may require this type of script very occasionally, but I am sharing because this is also one of the necessary scripts for PostgreSQL DBA.

This script will work after PostgreSQL 9.1.

Script to kill all running connections by specifying a database name:

SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE datname = 'datbase_name'
  AND pid <> pg_backend_pid();

Script to kill all running connections of a current database:

SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE datname = current_database()
  AND pid <> pg_backend_pid();

In this post, I am sharing different ways to show the currently running processes and sessions in MySQL.

Also, I am sharing a command for killing any running or sleep process.

When DBA is monitoring the database, it requires to find and kill some unwanted processes of MySQL Server.

How to find running processes or sessions?

Below are three different ways:

SELECT * 
FROM INFORMATION_SCHEMA.PROCESSLIST 
WHERE COMMAND != 'Sleep';

show  processlist;

/*Execute using MySQL Console*/
mysqladmin -u root -p -i 1 processlist;

How to kill running processes or sessions?

KILL CONNECTION <processid>