Book Image

PostgreSQL 16 Administration Cookbook

By : Gianni Ciolli, Boriss Mejías, Jimmy Angelakos, Vibhor Kumar, Simon Riggs
5 (1)
Book Image

PostgreSQL 16 Administration Cookbook

5 (1)
By: Gianni Ciolli, Boriss Mejías, Jimmy Angelakos, Vibhor Kumar, Simon Riggs

Overview of this book

PostgreSQL has seen a huge increase in its customer base in the past few years and is becoming one of the go-to solutions for anyone who has a database-specific challenge. This PostgreSQL book touches on all the fundamentals of Database Administration in a problem-solution format. It is intended to be the perfect desk reference guide. This new edition focuses on recipes based on the new PostgreSQL 16 release. The additions include handling complex batch loading scenarios with the SQL MERGE statement, security improvements, running Postgres on Kubernetes or with TPA and Ansible, and more. This edition also focuses on certain performance gains, such as query optimization, and the acceleration of specific operations, such as sort. It will help you understand roles, ensuring high availability, concurrency, and replication. It also draws your attention to aspects like validating backups, recovery, monitoring, and scaling aspects. This book will act as a one-stop solution to all your real-world database administration challenges. By the end of this book, you will be able to manage, monitor, and replicate your PostgreSQL 16 database for efficient administration and maintenance with the best practices from experts.
Table of Contents (15 chapters)
13
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14
Index

Checking whether a user is connected

Here, we will show you how to find out whether a certain database user is currently connected to the database.

Getting ready

If you are logged in as a superuser, you will have full access to monitoring information.

How to do it…

Issue the following query to see whether the user bob is connected:

SELECT datname FROM pg_stat_activity WHERE usename = 'bob';

If this query returns any rows, then that means that bob is connected to the database. The returned value is the name of the database that the user is connected to.

How it works…

PostgreSQL’s pg_stat_activity system view keeps track of all running PostgreSQL backends. This includes information such as the query that is being currently executed, the last query that was executed by each backend, who is connected, when the connection, transaction, and/or query were started, and so on.

There’s more…

Please spend a...