This Presentation I used in OSI-Days conference @ Bangalore on 14th Oct, 2012.

1. <Insert Picture Here>
MySQL Performance Schema
(OSI, 14th Oct, 2012)
Mayank Prasad
Sr. Software Engineer, MySQL-Oracle

2. Safe Harbor Statement
The following is intended to outline our general product direction. It is
intended for information purposes only, and may not be incorporated
into any contract. It is not a commitment to deliver any material, code,
or functionality, and should not be relied upon in making purchasing
decision. The development, release, and timing of any features or
functionality described for Oracle’s products remains at the sole
discretion of Oracle.
2Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

3. Agenda

What is Performance Schema

Origin and Development

Design

Configuration

Server Variables and Status Variables

Tables in Performance Schema

An Example

Benefits of Performance Schema

Drawbacks of Performance Schema

What's new in MySQL-5.6

Q/A.

Reference
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4. Why Performance Schema ??

End user: why is my session stuck ?

MySQL developer: why is this code contended ?

App developer: why is my application slow ?

DBA: why is this table hot ?

Storage: why is this disk spinning ?

Network: why is this link traffic high ?

System: why is the global throughput low ?
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5. What is Performance Schema
Performance Schema is a mechanism to give user a consolidated view
in a tabular format of what is happening behind the scene when
MySQL Server is running.
Information stored in tables. Can be accessed using SQL interface.
Not persistent tables i.e. not stored on disk. Once server is stopped,
all information in PS tables is gone.
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6. Origin and Development
Development was started by Marc Alff and Peter Gulutzan in 2008.
First introduced in MySQL-5.5 with minimal functionality.
Since then development is on full pace.
Next plan GA is MySQL-5.6 with number of new features introduced.
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7. Design
A new storage Engine : Performance Schema.
A new database : Performance Schema (with hard-coded DDL).
Instruments and instrumentation points in code.
Consumers.
Tracking events (Wait, Stage, Statements, Idle).
Timings.
Dynamic configuration for instruments/consumers.
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8. Design : Instrumentation
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9. Design : Instrumentation contd.
Instrumentation for :

I/O operations (File I/O, Table I/O, NET I/O)

Locking (mutex, rwlocks, table locks)

Waits

Statements

Stages

and so on ...
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10. Design : Event Waits Instrumentation
Monitored wait events.
Tables & Summary tables.
Instruments naming convention:
wait/io/file|socket|table
wait/lock
wait/synch/cond|mutex|rwlock
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11. Design : Event Wait Instrumentation contd.
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12. Design : Event Stage Instrumentation
Instrumented stage events.
Tables and Summary Tables.
Instruments naming convention:
stage/<code_area>/<stage_name
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13. Design : Event Stage Instrumentation contd.
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14. Design : Event Statements Instrumentation
Instrumented statement events.
Tables and Summary Tables.
Instruments naming convention:
statement/com|sql
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15. Design : Event Statements Instrumentation
contd.
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16. Nested Events
Statement
Stage
Wait
sync, lock, i/o
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17. Nested Events contd.
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18. Design : Timings
Available timers.
Timers setup in Performance
Schema.
Configurable option for any
instrument to be timed.
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19. Configuration
Compile time:
-DWITH_PERFSCHEMA_STORAGE_ENGINE=1
Server start-up: (enabled in 5.6 by default)
From configuration file:
[mysqld]
performance_schema=ON/1
performance_schema_consumers_<consumer_name>=on/true/1
performance_schema_events_waits_history_size=<some_number>
performance_schema_instruments='<instrument_name=on/true/1'
From command line:
l
--<all_above_options>
Runtime:
Update performance_schema.setup_consumers set ENABLED='YES' where
NAME='events_waits_history';
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20. Server Variables
Variables values at the run
time.
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21. Status Variables
Status information of
Performance Schema at run
time.
Used to inspect lost
information.
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22. Tables in Performance Schema
Total 52 tables (only 17 in 5.5)
Main category:
l
setup_tables
l
Instance_tables
l
wait_events_tables
l
stage_events_tables
l
statement_event_tables
l
connection_tables
l
connection_attribute_tables
l
summary_tables
l
miscellaneous_tables
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23. Tables in Performance Schema contd.
setup_consumers
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24. Tables in Performance Schema contd.
setup_instruments
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25. Tables in Performance Schema contd.
events_statements_summary_global_by_event_name
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26. Example to use PS to diagnose an issue
In a multi threaded scenario, thread_1 is stuck.
l
Find out what thread 1 is waiting for:
l
SELECT * FROM events_waits_current WHERE THREAD_ID = thread_1;
Say thread1 is waiting for mutex_A (Column OBJECT_INSTANCE_BEGIN).
l
Find out who has taken mutex_A.
l
SELECT * FROM mutex_instances WHERE OBJECT_INSTANCE_BEGIN = mutex_A;
thread_2 is holding mutex_A. (Column LOCKED_BY_THREAD_ID)
l
Find out what thread_2 is waiting for:
l
SELECT * FROM events_waits_current WHERE THREAD_ID = thread_2;
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27. Benefits of Performance Schema
l
Great insight of a running MySQL server.
l
Good granularity of information (nested events).
l
Available irrespective of platforms.
l
User friendly with well known SQL interface.
l
Multiple summary tables to give consolidated view to user.
l
Can be configured to meet user's need at run time.
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28. Drawbacks of Performance Schema
Only drawback is impact on performance.
Depends on PS configuration. All enable, noticeable hit.
Improved significantly in 5.6 and enabled by default. Less then 5%
with default instrumentation enabled.
Getting better and better …
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29. Whats new in MySQL-5.6
Instrumenting Table I/O.
Instrumenting Table Lock.
Instrumenting NET I/O.
Instrumenting Stages.
Instrumenting Statements.
Multiple summary tables.
Host cache.
... and many more.
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30. Reference
MySQL documentation:
http://dev.mysql.com/doc/refman/5.6/en/performance-schema.html
PS overhead analysis:
http://dimitrik.free.fr/blog/archives/2012/06/mysql-performance-pfs-overhead-in-56.html
Blogs :
http://marcalff.blogspot.com/
http://www.markleith.co.uk/
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31. <Insert Picture Here>
Thanks for attending!

32. MySQL at Glance
OSI, October 12-14, Bangalore
Sessions are happening at
10/12 Workshop “MySQL Performance Tuning”
10/13 Workshop “MySQL Cluster”
10/14
- 09:45-10:30 Keynote “The State Of The Dolphin”
- 10:30-11:15 Session “MySQL Is Exciting Again”
- 12:45-13:30 Session “Mysql 5.6 Optimizer Improvements”
- 14:15-15:00 Panel Discussion “FOSS Fueled Innovation”
- 15:45-16:30 Session “MySQL Cluster With A Mix & Match Of In-Memory Database & No SQL”
- 16:30-17:15 Session “MySQL Performance Schema”
Come and meet with MySQL Engineers and Experts and join us with
“Live Workshop” at our booth!!
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