Cost of a Join

Published: Sun 05 August 2018
By Brian Davis
In Posts.

tags: postgresql

How expensive is a join?

It depends! It depends what the join criteria is, what indexes are present, how big the tables are, whether the relations are cached, what hardware is being used, what configuration parameters are set, whether statistics are up-to-date, what other activity is happening on the system, to name a few things.

But we can still try and get a feel for what a couple simple scenarios look like and see what happens when: