Tomas Vondra

POSETTE 2024 Talk

Where do the performance cliffs come from?

local CEST (Livestream 4)

When running queries on a Postgres database, chances are you have experience with hitting a "performance cliff" - an abrupt change of performance for a given Postgres query, after only a small change in data and/or query parameters.

In this talk, you'll learn why performance cliffs happen in Postgres. After a brief explanation of how cost-based optimizers work and what assumptions that relies on, I'll show a couple examples why/how it fails. I'll also share recommendations on how to mitigate these issues.

If time permits, I'll talk about a couple interesting improvements & possible solutions proposed in recent research projects, focused on making Postgres query execution more adaptive & robust.