1.

• Making MySQL fast Richard Cunningham (@rythie)

2. FriendBinder

3.

How to measure

• MySQL slow query log

4. 'Explain Extended' feature of MySQL

5. Apache custom logs, page load time (%D) 6. mysql> show processlist; 7. iostat -x 10 / munin / RDDtool etc. 8. On FriendBinder we have (in dev. mode):

• • a page timer
• 9. Explain extended and times for all queries on page

10. Page load times recorded for all users

11.

Hard Disks

Sequential performance performance of 'spinning' disk is120Mb/sec , 1GBit network can only do 125Mb/sec, sounds good, but... What about 4KB random reads?

• Fast Hard disk0.7MB/sec

12. consumer Intel SSD:64.3MB/sec

13. RAM~4-16,000MB/sec

source: Anandtech: http://j.mp/g4lD6w

14.

Indexes

• MySQL only uses one index per table for each query

15. A index can cover several columns but can't miss one

16. Examples... 17. WHERE user=1 AND pub_date=NOW() AND id=34 18. WHERE user=1 AND id=34 19. WHERE user=1 AND pub_date < NOW() AND id=34 User pub_date id User pub_date id User pub_date id 20.

Covering Indexes

A covering index is one all of the query can be resolved from the index including the WHERE, JOIN and SELECT parts.

Covering...

21. SELECT date_pub FROM table1 22. WHERE User=2 23. Not covering... 24. SELECT name FROM table1 25. WHERE user=2 User pub_date id User pub_date id 26.

Clustered Indexes

In the MyISAM table type new records are simply added to the end of file. Problem is that queries often are jumping all around the file.

In InnoDB the records are stored in order of the primary key

27.

What not to index

• Binary columns - these are not selective enough, MySQL will never use it

28. Subset indexes of other indexes

29. Anything you don't have a query for design indexes for queries User pub_date User pub_date id 30.

Further Information

• This book has more...

Contacting me:

@rythie

31. www.rythie.com 32. [email_address]