About this project

Hello !

You may be on this repository because you have seen my talk on EXPLAIN. Welcome !

On this repository you will find a dump of the database, a few SQL lines used to generate data, and the queries used during this talk.

Lost the slides ?

Here they are

How to get started with this project ?

Create the database

First you need to create a database

CREATE DATABASE owl_conference WITH OWNER owl;

Then you can simply use the dump, in your shell

$ psql owl_conference < sql/dump.sql

I put the code using generate_series that I used to generate humans and letters (with random foreign keys to humans). You can see that in sql/01_generate_data.sql

Test the python joins

Use a virtualenv with django and psycopg2 installed.

Then you can do

$ python manage.py shell

Try the hash_join and the nested_loop like this

>>> from owl.utils.joins import *
>>> data = nested_loops()
>>> print(data[0].job)
>>> data = hash_join()
>>> print(data[0].job)

You can try the suspicious_letters from the slide 44 of the talk by running in the python shell

>>> from owl.utils.examples import *
>>> data = suspicious_letters()
>>> print(data)

Test the queries

In the sql/02_queries.sql you have all the queries from the conference. The last one is the funiest one ;)

Go into your psql and try looking at the EXPLAIN :)

$ psql owl_conference