Book Image

PostgreSQL 11 Administration Cookbook

By : Simon Riggs, Gianni Ciolli, Sudheer Kumar Meesala
Book Image

PostgreSQL 11 Administration Cookbook

By: Simon Riggs, Gianni Ciolli, Sudheer Kumar Meesala

Overview of this book

PostgreSQL is a powerful, open source database management system with an enviable reputation for high performance and stability. With many new features in its arsenal, PostgreSQL 11 allows you to scale up your PostgreSQL infrastructure. This book takes a step-by-step, recipe-based approach to effective PostgreSQL administration. The book will introduce you to new features such as logical replication, native table partitioning, additional query parallelism, and much more to help you to understand and control, crash recovery and plan backups. You will learn how to tackle a variety of problems and pain points for any database administrator such as creating tables, managing views, improving performance, and securing your database. As you make steady progress, the book will draw attention to important topics such as monitoring roles, backup, and recovery of your PostgreSQL 11 database to help you understand roles and produce a summary of log files, ensuring high availability, concurrency, and replication. By the end of this book, you will have the necessary knowledge to manage your PostgreSQL 11 database efficiently.
Table of Contents (19 chapters)
Title Page
Copyright and Credits
About Packt

Knowing who is blocking a query

Once you have found out that a query is being blocked, you need to know who or what is blocking it.

Getting ready

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

How to do it…

Perform the following steps:

  1. Write the following query:
SELECT datname, usename, wait_event_type, wait_event, pg_blocking_pids(pid) AS blocked_by, backend_type, query
FROM pg_stat_activity
WHERE wait_event_type IS NOT NULL
AND wait_event_type NOT IN ('Activity', 'Client');
  1. You will receive the following output:
-[ RECORD 1 ]---+-----------------
datname         | postgres
usename         | gianni
wait_event_type | Lock
wait_event      | relation
blocked_by      | {18142}
backend_type    | client backend
query           | select * from t;

This is, in fact, the query we described in the previous recipe, with the addition of the blocked_by column. Recall that the PID is the unique identifier assigned by the operating system to each session; for more details...