Skip to Content
PostgreSQL 10 Administration Cookbook - Fourth Edition
book

PostgreSQL 10 Administration Cookbook - Fourth Edition

by Simon Riggs, Gianni Ciolli
May 2018
Intermediate to advanced content levelIntermediate to advanced
576 pages
30h 25m
English
Packt Publishing
Content preview from PostgreSQL 10 Administration Cookbook - Fourth Edition

There's more…

If you have multi-column indexes (or joins), the optimizer will assume that the column values are independent of each other, which can lead to mis-estimation in cases where there is a correlation between the values.

If you have two dependent columns, such as state and area_code, then you can define additional statistics that will be collected when you next ANALYZE the table:

CREATE STATISTICS cust_s1 (ndistinct, dependencies) ON state, area_code FROM cust;

Execution time of ANALYZE will increase to collect the additional stats information, plus there is a small increase in query planning time so use this sparingly when you can confirm this will make a difference. You don’t need to have both ndistinct and dependencies in all ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

PostgreSQL 13 Cookbook

PostgreSQL 13 Cookbook

Vallarapu Naga Avinash Kumar
PostgreSQL 9 Administration Cookbook - Second Edition

PostgreSQL 9 Administration Cookbook - Second Edition

Simon Riggs, GIANNI CIOLLI, Hannu Krosing, Gabriele Bartolini

Publisher Resources

ISBN: 9781788474924Supplemental Content