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Designing Scalable
Architectures
with MySQL Proxy
Giuseppe Maxia
MySQL Community Team Leader - Sun Microsystems
John Loehrer
Data Architect, Gaia Online
Jimmy Guerrero
Sr Product Marketing Manager - Sun Microsystems, Database Group
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
1
Agenda
•
•
•
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Proxy concepts
MySQL Proxy architecture
Proxy with a single back-end
Proxy with multiple back-ends
broken?
•
• missing feature?
• not flexible?
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
traditional way
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
traditional way
1.
file a bug report
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
traditional way
1.
2.
file a bug report
wait
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
traditional way
1.
2.
file a bug report
wait
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
•
Open source way
source
code
compile
new
source
code
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
modify
Solving database problems
•
creative (shortsighted) way
bring the logic
at application
level
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
•
creative (enlightened) way
set the logic at
server level
(stored
routines)
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Solving database problems
•
creative (more enlightened) way
set the logic at
protocol level
(proxy)
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
what can you do with MySQL Proxy
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•
•
•
•
•
•
•
•
•
•
•
create new commands
filter queries (deny specific queries)
collect statistics on usage
implement usage quotas
execute shell commands
create customized logs
implement server-side pivot tables
start/stop a MySQL server remotely
play movies (seriously!)
make coffee (really?)
sharding
load balancing servers
Basic principles
Basic principles
PROXY
CORE
Lua script
connection
hook
function
function
function
read query
hook
function
read result
hook
function
Lua
??
Why not ...
{
Perl ?
PHP?
Javascript?
[whatever]?
Lua
• SMALL ( < 200 KB)
• DESIGNED for
EMBEDDED systems
• Widely used (lighttpd)
lighttpd, like MySQL
Proxy, was created by
Jan Kneschke
Lua
Very popular among
game writers
Proxy overview
global
context
Lua script
connect_server
session
context
session
context
session
context
session
context
session
context
session
context
session
context
read_handshake
read_auth
read_auth_result
read_query
read_query_result
disconnect_client
Proxy overview
/usr/local/sbin/mysql-proxy \
--proxy-lua-script=/path/name.lua
IMPORTANT!
THE SCRIPT DOES NOT START UNTIL THE FIRST
CLIENT CONNECTION
read_query and read_query_result
client
query
result
function
read_query
function
read_query_result
MySQL
Proxy
query
result
SERVER
if a query is passed directly to the
server, its result is NOT evaluated
by read_query_result
read_query and read_query_result
client
query
result
function
function
read_query
read_query_result
MySQL
Proxy
query queue
query
query
query
result
SERVER
only if a query is
added to the query
queue, its result is
evaluated by
read_query_result
An example: user quotas
•
•
•
You want to limit user access
When the user reaches a given amount of data,
further queries should be rejected
the quota must work across sessions
(code online)
http://forge.mysql.com/tools/tool.php?id=111
User quotas
-- some global variables
-- proxy.global.bandwidth
-- will sum up the used bytes
proxy.global.bandwidth
= proxy.global.bandwidth or {}
-- session_user will identify the user
-- throughout the session
local session_user
User quotas
-- session_user needs to be initialized
-- when the user information is passed
-- (during the authentication)
function read_auth( auth )
session_user = auth.username
proxy.global.bandwidth[session_user]
= proxy.global.bandwidth[session_user]
or 0
end
BREAK (a handy Lua idiom)
-- simple assignment
a = a or 0
-- corresponds to:
if a == nil
then
a = 0
else
a = a
end
if a ~= nil
then
a = a
else
a = 0
end
BREAK (a handy Proxy Lua function )
-- returns an error to the client
function error_result (msg)
proxy.response = {
type
=
proxy.MYSQLD_PACKET_ERR,
errmsg
= msg,
errcode
= 7777,
sqlstate
= 'X7777',
}
return proxy.PROXY_SEND_RESULT
end
User quotas
-- read_query (1)
-- checking if the quota has been
-- exceeded
function read_query (packet )
if proxy.global.bandwidth[session_user]
> 10000
and session_user ~= 'root'
then
return error_result(
'you have exceeded your query quota')
end
-- ...
User quotas
-- read_query (2)
-- adding to the totalizer
-- ...
proxy.global.bandwidth[session_user ]
=
proxy.global.bandwidth[session_user]
+ packet:len()
proxy.queries:append(1, packet )
return proxy.PROXY_SEND_QUERY
end
User quotas
-- read_query_result (1)
-- adding row headers to the totalizer
function read_query_result(inj)
local fields = inj.resultset.fields
local rows = inj.resultset.rows
if fields then
for i = 1, #fields do
proxy.global.bandwidth[session_user]
=
proxy.global.bandwidth[session_user]
+
(fields[i] and fields[i].name:len() or 0)
end
User quotas
-- read_query_result (2)
-- adding rows contents to the totalizer
if rows then
for row in rows do
for i = 1, #fields do
proxy.global.bandwidth[session_user]
=
proxy.global.bandwidth[session_user]
+
(row[i] and row[i]:len() or 0)
end
end
end
end
User quotas
-- read_query_result (3)
-- displaying the current bandwidth
end
print (session_user .. ' -> ' ..
proxy.global.bandwidth[session_user])
User quotas - what the user sees
mysql> select repeat('a', 10000);
ERROR 7777 (X7777): you have exceeded your
query quota
User quotas (VERY advanced)
------
you can create another module
to be loaded at run time
(this is really advanced)
and in such module you define
a SHOW QUOTAS command
User quotas (VERY advanced)
-- load_multi
User quotas (VERY advanced)
mysql> pload show_quotas.lua;
+--------------------------------+
| info
|
+--------------------------------+
| module "show_quota.lua" loaded |
+--------------------------------+
mysql> show quotas;
+----------+-------+
| name
| quota |
+----------+-------+
| simple
| 3578 |
| root
| 2111 |
| msandbox | 102
|
+----------+-------+
Designing Scalable
Architectures
with MySQL Proxy
Giuseppe Maxia
MySQL Community Team Leader - Sun Microsystems
John Loehrer
Data Architect, Gaia Online
Jimmy Guerrero
Sr Product Marketing Manager - Sun Microsystems, Database Group
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
36
quick-start guide to mysql muxing
ME
online hangout
for teens
5 million unique users per month
1.3 billion forum entries
How does Gaia use the proxy?
connection multiplexer
turning 7,500 connections ...
into 100 MySQL connections
MySQL Proxy
7,500 connections
PHP
100 connections
MySQL
Server
Why MUX?
a little history ...
Gaia’s data center in 2003
our server farm...
as our site grew ...
some scaling issues
added more servers ...
site explodes
diagnose the problem
GAIA, under the hood
typical LAMP stack
Linux
Share-Nothing Architecture
each apache server = 50 connections
Parent
Process
httpd
child httpd
worker thread
worker thread
child httpd
...
listener thread
...
50 connections * 150 servers = stampede
close connections each time
setup / tear-down is expensive
connecting to MySQL
connect
read
challenge
write
auth
read
auth OK
connect
read
challenge
write
auth
read
auth OK
write query read result
75%
connect
read
challenge
write
auth
read
auth OK
19%
6%
write query read result
close
MySQL Thread spawning
Client
Client
connect
MySQL Server
Client
connect
MySQL Server
Client
MySQL Server
Thread
connect
new
Client
MySQL Server
Thread
connect
new
accept
threads stack up
MySQL I/O
listen
accept
listen
close
end program
NEW THREAD
accept
listen
close
end program
accept
NEW THREAD
blocking read
listen
close
end program
accept
NEW THREAD
blocking read
data
blocking write
listen
close
accept
end program
NEW THREAD
blocking read
data
eof
close
blocking write
close thread
talking to multiple databases ...
Forum Page
Session DB
start session
get userdata
get topic
get related users
save session
User DB
Forum DB
idle threads
we need a connection pool
ideally ...
Event Queue
Thread Pool
Thread
allocate thread
process query
free
release the thread after each query
it’s like a limo ...
... vs. a taxi
decouple threads from connections
Libevent’s callback I/O very sweet!
listen
register callback
event dispatch
active descriptor
Trigger callback
epoll/kqueue rulez! (proxy uses it)
MySQL 6.0 taking the right steps ...
In the meantime ...
by default, mysql-proxy isn’t a pooler
lua hooks are awesome!
hack some lua scripts ...
goal: recycle back-end connections
keep clients connected
proxy stays transparent
how to twist the proxy into a pooler
connecting: find an idle back-end
Proxy
client
Proxy
client
connect ahead
idle pool
authentication
Client
Proxy
Back-End Pool
MySQL Server
Client
Proxy
Back-End Pool
MySQL Server
Client
Proxy
connect
Back-End Pool
MySQL Server
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
com-change-user
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
com-change-user
challenge
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
com-change-user
challenge
authenticate
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
com-change-user
challenge
authenticate
OK
Client
Proxy
Back-End Pool
MySQL Server
connect
allocate
com-change-user
challenge
authenticate
OK
free back-end
run the query
don’t be afraid to let go
Client
Proxy
query
Client
Proxy
Back-End Pool
query
allocate
Client
Proxy
Back-End Pool
MySQL Server
query
allocate
process query
Client
Proxy
Back-End Pool
MySQL Server
query
allocate
process query
free back-end
connections scale!
Designing Scalable
Architectures
with MySQL Proxy
Giuseppe Maxia
MySQL Community Team Leader - Sun Microsystems
John Loehrer
Data Architect, Gaiaonline
Jimmy Guerrero
Sr Product Marketing Manager - Sun Microsystems, Database Group
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Copyright 2008
MySQL AB
The World’s Most Popular Open Source Database
160
MySQL Load Balancer
MySQL software which can route database queries to
the appropriate database in a scale-out environment.
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•
•
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Intelligently route reads across slaves
Use database least behind, least loaded
Remove latent slaves from read rotation
Other distribution algorithms
• Improves/scales throughput of reads for online applications
• Helps customers reduce cost of adding slaves
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
161
MySQL Query Analyzer
MySQL Enterprise Monitor feature that allows users
to trace, monitor, and analyze MySQL query activity
for specific servers, users, and applications.
• Adaptive “Evil” query collection/tracing
• Historical browsing/analysis
• “Needle in a haystack” identification of worst
queries
• Worst execution times, # of execs, etc.
SQL code is the #2 cause of performance issues
97% of those surveyed will use this
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
162
MySQL Query Analyzer
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
163
MySQL Proxy Forum
Next Steps
http://forums.mysql.com/list.php?146
Documentation – MySQL Proxy
http://dev.mysql.com/doc/refman/5.1/en/mysql-proxy.html
Documentation – MySQL Load Balancer
http://dev.mysql.com/doc/refman/5.1/en/load-balancer.html
Beta Testing MySQL Proxy-Enabled Products
[email protected]
MySQL Proxy Online Poll
http://dev.mysql.com/tech-resources/quickpolls/
Copyright 2008 MySQL AB
The World’s Most Popular Open Source Database
164
Questions?
Giuseppe Maxia
MySQL Community Team Leader - Sun Microsystems
John Loehrer
Data Architect, Gaiaonline
Jimmy Guerrero
Sr Product Marketing Manager - Sun Microsystems, Database Group
This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Copyright 2008
MySQL AB
The World’s Most Popular Open Source Database
165
