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Mastering PostgreSQL 12 - Third Edition
book

Mastering PostgreSQL 12 - Third Edition

by Hans-Jürgen Schönig
November 2019
Beginner to intermediate content levelBeginner to intermediate
470 pages
11h 59m
English
Packt Publishing
Content preview from Mastering PostgreSQL 12 - Third Edition

Enabling and disabling optimizer settings

So far, the most important optimizations that are performed by the planner have been discussed in detail. PostgreSQL has improved a lot over the years. Still, something can go south and users have to convince the planner to do the right thing.

To modify plans, PostgreSQL offers a couple of runtime variables that will have a significant impact on planning. The idea is to give the end user the chance to make certain types of nodes in the plan more expensive than others. What does that mean in practice? Here is a simple plan:

test=# explain SELECT *  FROM generate_series(1, 100) AS a,  generate_series(1, 100) AS b  WHERE a = b;                                     QUERY PLAN                                     ------------------------------------------------------------------------------------ ...
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Publisher Resources

ISBN: 9781838988821Supplemental Content