I gave this presentation about the totally awesome mysqlnd_ms PHP extension at the Minnesota PHP User Group.

1. Intro to PECL/mysqlnd_ms
Chris Barber
Minnesota PHP User Group
April 7, 2011

2. About Me
Chris Barber
Lead Software Engineer @ Appcelerator
CEO/Technology Consultant @ CB1, INC.
JavaScript, PHP, C++
http://www.cb1inc.com
@cb1kenobi on Twitter, Slideshare

3. What is mysqlnd?

4. What is mysqlnd?
MySQL Native Driver for PHP
PHP 5.3+
Replaces libmysql
Used by ext/mysql, ext/mysqli, PDO_MYSQL
Use configure options: --with-mysql=mysqlnd --with-
mysqli=mysqlnd --with-pdo-mysql=mysqlnd
Not compiled into Ubuntu’s PHP 5.3 package :(

5. What is mysqlnd_ms?

6. What is mysqlnd_ms?
A PHP Extension that provides transparent MySQL
load balancing across master and slave servers

7. How it works
Create a mysqlnd_ms_config.ini with your settings
Make MySQL calls from your PHP code
INSERT, UPDATE, & DELETE statements go to master
SELECT statements go to slaves

8. Getting started

9. php.ini
extension=mysqlnd_ms.so
mysqlnd_ms.enable=1
mysqlnd_ms.ini_file=mysqlnd_ms_config.ini

10. mysqlnd_ms_config.ini
[myapp]
master[]=192.168.1.120
slave[]=192.168.1.121
slave[]=192.168.1.122

11. PHP Usage
<?php
$db = mysqli(“myapp”, “user”, “password”);
$results = $db->query(“SELECT ...”);
$db->query(“INSERT ...”);
?>

12. Which server to connect to?

13. Choosing a server
Available load balancing algorithms:
random
round-robin
user defined (custom PHP function)
random_once (sticky)
Specify algorithm in the mysqlnd_ms_config.ini file

14. Choosing a server
[myapp]
master[]=192.168.1.120
slave[]=192.168.1.121
slave[]=192.168.1.122
pick[]=user
pick[]=random
<?php
function pick_server($connected_host, $query, $master, $slaves, $last_used_connection) {
if (stristr($query, “FROM table_a”))
return “hostname_of_slave_for_table_a”;
return NULL; // resort to random/random-once/round-robin
}
mysqlnd_ms_set_user_pick_server(“pick_server”);
?>

15. Issues...

16. Issues
INSERT and immediate SELECT
Replication lag
Transactions
Need server stickiness
Failover

17. Hints
Prefix query with a comment!
<?php
$db = mysqli(“myapp”, “user”, “password”);
$results = $db->query(“/* HINT_GOES_HERE */SELECT ...”);
?>

18. Built-in Hints
MYSQLND_MS_MASTER_SWITCH
MYSQLND_MS_SLAVE_SWITCH
MYSQLND_MS_LAST_USED_SWITCH
MYSQLND_MS_ALL_SERVER_SWITCH
MYSQLND_MS_QUERY_USE_MASTER
MYSQLND_MS_QUERY_USE_SLAVE
MYSQLND_MS_QUERY_USE_LAST_USED

19. Hints
<?php
$db->query(sprintf(“/*%s*/SET @a=1”, MYSQL_MS_SLAVE_SWITCH));
$db->query(sprintf(“/*%s*/SET @a=@a+1”, MYSQL_MS_LAST_USED_SWITCH));
$db->query(sprintf(“/*%s*/SELECT @a as _a”, MYSQL_MS_LAST_USED_SWITCH));
?>

20. Custom Hints
<?php
function pick_server($connected_host, $query, $master, $slaves, $last_used_connection) {
if (preg_match("@^/*.+*/@ismU", $query, $matches)) {
$json = json_decode($matches[1])
if ($json && $json->something_enabled) {
return “some_special_hostname”;
}
}
return NULL; // resort to random/random-once/round-robin
}
mysqlnd_ms_set_user_pick_server(“pick_server”);
$db->query(“/* {“something_enabled”:true} */SELECT ...”);
?>

21. Server Picking Ideas
Geo-load balancing
Routing around server maintenance
Sharding
Dynamically add/override master/slave hostnames

22. Failover
mysqlnd_ms does not do failover
Do it in your application!
Retry query N number of times before falling on sword
Have pick_server() “disable” dead servers for a minute
Perhaps use APC to cache which servers are dead

23. Getting mysqlnd_ms
svn co http://svn.php.net/repository/pecl/mysqlnd_ms/
trunk mysqlnd_ms
cd mysqlnd_ms
phpize
configure
make
sudo make install

24. More Info
Authors: Andrey Hristov, Ulf Wendel, & Johannes
Schlueter
http://blog.ulf-wendel.de
http://svn.php.net/viewvc/pecl/mysqlnd_ms

25. Thanks
Questions?