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PostgreSQL Administration Cookbook, 9.5/9.6 Edition

You're reading from   PostgreSQL Administration Cookbook, 9.5/9.6 Edition Effective database management for administrators

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Product type Paperback
Published in Apr 2017
Publisher
ISBN-13 9781785883187
Length 556 pages
Edition 3rd Edition
Languages
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Authors (4):
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Gianni Ciolli Gianni Ciolli
Author Profile Icon Gianni Ciolli
Gianni Ciolli
Hannu Krosing Hannu Krosing
Author Profile Icon Hannu Krosing
Hannu Krosing
Gabriele Bartolini Gabriele Bartolini
Author Profile Icon Gabriele Bartolini
Gabriele Bartolini
Simon Riggs Simon Riggs
Author Profile Icon Simon Riggs
Simon Riggs
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Toc

Table of Contents (13) Chapters Close

Preface 1. First Steps FREE CHAPTER 2. Exploring the Database 3. 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

Carefully removing unwanted indexes

Carefully removing? You mean press Enter gently after typing DROP INDEX? Err, no!

The thinking is that it takes a long time to build an index, and a short time to drop it.
What we want is a way of removing an index such that if we discover that removing it
was a mistake, we can put the index back again quickly.

Getting ready

The following query will list all invalid indexes, if any:

SELECT ir.relname AS indexname 
, it.relname AS tablename
, n.nspname AS schemaname
FROM pg_index i
JOIN pg_class ir ON ir.oid = i.indexrelid
JOIN pg_class it ON it.oid = i.indrelid
JOIN pg_namespace n ON n.oid = it.relnamespace
WHERE NOT i.indisvalid;

Take note of these indexes, so that later you can tell whether...

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