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PostgreSQL 16 Administration Cookbook

You're reading from   PostgreSQL 16 Administration Cookbook Solve real-world Database Administration challenges with 180+ practical recipes and best practices

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Product type Paperback
Published in Dec 2023
Publisher Packt
ISBN-13 9781835460580
Length 636 pages
Edition 1st Edition
Languages
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Authors (5):
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Boriss Mejías Boriss Mejías
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Boriss Mejías
Jimmy Angelakos Jimmy Angelakos
Author Profile Icon Jimmy Angelakos
Jimmy Angelakos
Simon Riggs Simon Riggs
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Simon Riggs
Gianni Ciolli Gianni Ciolli
Author Profile Icon Gianni Ciolli
Gianni Ciolli
Vibhor Kumar Vibhor Kumar
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Vibhor Kumar
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Toc

Table of Contents (15) Chapters Close

Preface 1. First Steps 2. Exploring the Database FREE CHAPTER 3. Server Configuration 4. Server Control 5. Tables and Data 6. Security 7. Database Administration 8. Monitoring and Diagnosis 9. Regular Maintenance 10. Performance and Concurrency 11. Backup and Recovery 12. Replication and Upgrades 13. Other Books You May Enjoy
14. Index

How many rows are there in a table?

There is no limit on the number of rows in a table, but the table is limited to available disk space and memory/swap space. If you are storing rows that exceed an aggregated data size of 2 KB, then the maximum number of rows may be limited to 4 billion or fewer.

Counting is one of the easiest SQL statements, so it is also many people’s first experience of a PostgreSQL query.

How to do it…

From any interface, the SQL command used to count rows is as follows:

SELECT count(*) FROM table;

This will return a single integer value as the result.

In psql, the command looks like the following:

cookbook=# select count(*) from orders;
count
-------
   345
(1 row)

How it works...

PostgreSQL can choose between two techniques available to compute the SQL count(*) function. Both are available in all the currently supported versions:

  • The first is called sequential scan. We access every data block in...
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PostgreSQL 16 Administration Cookbook
Published in: Dec 2023
Publisher: Packt
ISBN-13: 9781835460580
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