The document discusses HyperDB, which powers the database functionality of WordPress.com. It notes that while HyperDB may seem complex, it is mostly configuration that takes advantage of advanced MySQL features like replication, partitioning, and load balancing. The document provides an overview of these MySQL features and best practices for MySQL performance monitoring, query analysis, and maintenance. It also discusses different MySQL flavors like MariaDB and Percona and tools like Percona Toolkit.

1. Anthropomorphic Design
Making a Better WordPress with Jazz Hands
+ =

2. But seriously….

3. HyperDB, MySQL
Performance, & Flavors of
MySQL
Evan Volgas

4. About me
• 10 years working with data — as an analyst, a
DBA, etc
• Currently a data engineer for WhatRunsWhere
• Data Engineer = DBA + Map Reduce + PTSD
from Apache Zookeeper
• Worked with WordPress off/on for about ~5 years

5. Disclaimers
I believe
• Google exists
• You can use it
• You don’t enjoy reading a bunch of code and
config files in a presentation any more than I do
• WordCamp needs more cowbell

6. What is
HyberDB?
• “Very advanced database class”
• Powers WordPress.com
• Supports replication, partitioning, load balancing,
etc

7. “Very advanced database class”
find 'hyperdb/' -name '*.php' | xargs wc -l
• HyperDB: 1,401 lines of PHP
• WordPress: 255,961 lines of PHP
• Hello Dolly: 81 lines of PHP
• Yoast’s Google Analytics 16,174 lines of PHP

8. Why’d you have to go and make
things so complicated
• The complexity of HyperDB has nothing to do with
the PHP code itself
• Implementing HyperDB itself is mostly
configuration
• To the extent that HyperDB is advanced, it’s
because MySQL has a lot of advanced stuff going
on underneath the hood

9. Who cares about MySQL?
An argument from fellow WordCamp ATL
presenter Tom McFarlin*
• Employers haven’t fully figured out what
WordPress *can* do
• WordPress makes it easy to be a software
implementer as opposed to a software
developer so in a lot of cases salaries probably
should be lower
• The WordPress community itself hasn’t
educated employers, customers, or software
implementors how classical software
development / engineering can fit into the
WordPress ecosystem
*https://tommcfarlin.com/wordpress-developer-
salary/

10. Tell me again why this matters
• We don’t need any more social media icons plugin
• Many of the things that are really pushing the
WordPress envelope are VERY database
intensive and their performance needs are poorly
understood
• There are a million things you can (and should) do
to optimize your WordPress website. When those
stop being enough, it’d be a good idea to know
some DB basics

11. HyperDB
• For practical extents and purposes, it’s kind of like a
giant wp-config.php that pertains to your database
• A lot of great resources for setting it up. If you
decide you want to try it, make sure you check out
https://www.digitalocean.com/community/tutorials/how-to-optimize-wordpress-
performance-with-mysql-replication-on-ubuntu-14-04
http://wpguru.co.uk/2010/07/testing-hyperdb/
http://codertalks.com/configuring-hyperdb-to-use-multiple-databases-for-buddypress-
multisite/

12. MySQL Lingo + Discussion
• Replication
• Statement vs Row-based
• Master vs Slave
• Partitioning
• Tends to either really help or really hurt you — very little in between
• NB: One of the reasons NoSQL has market adoption is because this is very painful
• Latency matters: https://gist.github.com/jboner/2841832
• Failover
• Load Balancing
• DB: HyperDB
• Web app: HA Proxy, Nginx, etc

13. MySQL Performance Basics
• innodb_buffer_pool_size: 70-80% of memory is common
• innodb_buffer_pool_instances: if you have a lot of memory, you might
run into bottlenecks where multiple threads are trying to access the buffer
pool. Splitting it up into multiple buffer pools can help
• innodb_file_per_table: if you are using < MySQL 5.6, turn this on. Trust
me.
• max_connections: if you ever think you need to tweak this, double check
that your connections are terminating properly
• log_bin: your master nodes needs this
• slow-query-log, slow-query-log-file, long_query_time: log your slow
queries. Don’t go crazy, but periodically log everything and analyze it

14. MySQL Best Practices
Monitor everything
• New Relic, Datadog, Zabbix, graphite/statsd/collectd
• http://www.percona.com/live/mysql-conference-
2013/sites/default/files/slides/percona-live-santa-clara-2013-presentation-
spilgames-mysql-statsd.pdf <— Interesting idea
Analyze your queries
• pt-query-digest, mysqldumpslow, plugins for third party monitoring
Learn how to reason about the Query Execution Plan
• http://www.sitepoint.com/using-explain-to-write-better-mysql-queries/
Schedule DB maintenance

15. Flavors of MySQL
• MySQL
• MariaDB
• https://mariadb.com/blog/how-install-and-run-
wordpress-mariadb
• Percona:
• https://www.digitalocean.com/community/tutorials/ho
w-to-install-a-fresh-percona-server-or-replace-mysql

16. Special Mention
Percona Toolkit
• http://www.percona.com/doc/percona-toolkit/2.2/
pt-query-digest --since '2014-11-01' --filter '$event->{arg} =~ m/^select/i' /var/log/mysql/slow-query.log >
/tmp/pt_slow_since_nov2014
Nginx + PHP-FPM
• http://www.raspipress.com/2014/06/tutorial-install-wordpress-on-a-
raspberry-pi-using-nginx/
Learn from people within WordPress and from outside of it
• good example: https://roots.io/twelve-factor-wordpress/