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 whether anybody is using a specific table

This recipe helps you when you are in doubt about whether an obscure table is being used anymore, or if it has been left over from past use and is just taking up space.

Getting ready

Make sure that you are a superuser, or at least have full rights to the table in question.

How to do it…

Perform the following steps:

  1. To see whether a table is currently in active use (that is, whether anyone is using it while you are watching it), run the following query on the database you plan to inspect:
CREATE TEMPORARY TABLE tmp_stat_user_tables AS
       SELECT * FROM pg_stat_user_tables;


  1. Then, wait a little and see what has changed:
SELECT * FROM pg_stat_user_tables n
  JOIN tmp_stat_user_tables t
    ON n.relid=t.relid
   AND (n.seq_scan,n.idx_scan,n.n_tup_ins,n.n_tup_upd,n.n_tup_del)
    <> (t.seq_scan,t.idx_scan,t.n_tup_ins,t.n_tup_upd,t.n_tup_del);

How it works…

The pg_stat_user_tables view shows the current statistics for table usage.

To see whether...