How to get lost in your own country

Multiple times

Use Google Maps

About me

Veselin Nikolov

@dzver

WordPress.com

About me

Background as MS SQL DBA

Currently trying to keep things simple in a team of 10

Lessons from working on WordPress.com

WordCamp Romania 2014

What happened with the MySQL talk

One month ago

The reception

The questions

How do I make WordPress secure

What are your tips for secure WordPress

How do I chose save plugins and themes

How do you manage to work remotely?

Are there any other Bulgarians at Automattic?

! MySQL

There are no mistakes,only lessons.

... telling stories this time.

Story #1 The ID

7 year old legacy code

Entire table described in the code

We have items with ids 5 and 6. We need to add 7.

The 5 and 6 were repeated 135 times in the code.

Story #1 The ID

One new object

A few helpers

135 removed magic numbers

One changeset

0 unit tests

What could possibly go wrong?

Ups...

(I broke stuff)

Story #1 Lessons

Pleasepleaseplease, no magic numbers

Atomic commits, please!

Long functions are hard to understand

Stats monitoring

Legacy is code for which we don't have tests

Story #2 The Notification

Montreal

1+ million emails

1+ million discount coupons (10-ish previously)

Friday

What could possibly go wrong?

Story #2 The Notification

Queries that work with small tables:SELECT * FROM table

SELECT * FROM table ORDER BY whateverLIMIT 200, 100

Story #2 The Notification

Queries that don't work with large tables:SELECT * FROM table

SELECT * FROM table ORDER BY whateverLIMIT 200000, 100

Story #2 The Notification

Fetching big amounts of data breaks things

Offsetting breaks things

The coupons weren't really used in the past and didn't really work

Repeating millions of anything means a lot of time

Lessons

Launching big things on Friday

Offsets

SELECT * FROM ...WHERE `id` > 1093029ORDER BY `id` LIMIT 20

SELECT `deadline` FROM ...WHERE `date` BETWEEN '2014-06-20' AND ...

Offsets

SELECT * FROM ...WHERE `id` > 1093029ORDER BY `id` LIMIT 20

SELECT `deadline` FROM ...WHERE `date` BETWEEN '2014-06-20' AND ...

Offsets

SELECT * FROM `table` JOIN ( SELECT `id` FROM `table`ORDER BY `whatever`LIMIT 5000,50

) as `b` USING `id`

Story #3 The A/B Test

A/B test is showing different things to users and measuring effect

We use Kissmetrics

We've had 5 different A/B testing classes

Story #3 The A/B Test

Feature-rich classes

Many levels of abstraction

Expressive names

Many filters and actions

What could possibly go wrong?

Story #3 The A/B Test

class Server_Side_Experiment_Visitor extends Server_Side_Experiment_Base {...

Story #3 The A/B Test

Wrong results, no one knows why.

Story #3 The A/B Test

Wrong results, no one knows why.

Story #3 The A/B Test

A new colleague joins and writes this:ab_test('test-teh-button',array('orange','blue',

)

);// return 'orange'

Story #3 Lessons Learned

KISS. Simplest solution worked

Kissmetrics rocks

A/B test everything

Story #4 Barry

howdy hi, did I break anything? your blog looks hacked

Story #4

Unique passwords

2-factor auth

Come to WordCamp Europe and maybe watch Barry live :-)

#praythatbarrycomestowceurope

Summary

KISS. Simple queries. Simple code.

DRY. Repetition fails.

A/B test. Unit test. Test!

Launch your next project on Friday at 7pm.

My name is VeselinI code for food.

Ask me anything!