Database Performance
with Proxy Architectures
Tungsten SQL Router
Robert Hodges
CTO, Continuent, Inc.
Percona Performance Is Everything 2009
© Continuent 2009

The “Proxy Math” Problem
/ Proxy layers solve a number of database problems
• Seamless failover
• Intelligent load balancing
• Intelligent partitioning
/ Big Question: What’s the cost for applications?
/ Let’s run a few tests to show basic limits
• Simple queries with data guaranteed to be in buffer cache
• Dell SC 1425, Xeon 2 CPU x 2 Cores, 2.8Mhz
• No/minimal proxy logic
© Continuent 2009

Proxy Overhead Compared to Databases
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Proxy with Increasing Result Sizes
© Continuent 2009

How Do We Avoid Proxy Math?
/ Proxy performance is CPU intensive
• Mostly copying and transforming bytes
/ Bad case: 4x CPU resources for same throughput
• Could be far worse if proxy does more than copy data
• It’s not enough to make proxies faster
/ Alternative 1: Hardware load balancer
• If I only had a brain…
/ Alternative 2: VIPs
• Handy for availability but load balancing is a problem
/ Alternative 3: An embeddable library
• This would work on Amazon as well!
© Continuent 2009

Tungsten SQL Router Overview
/ Library-based intelligent failover and load balancing
/ Connection-level routing
/ Implemented as JDBC library wrapper (Java!)
• Adds intelligence to vendor drivers
/ DBMS-independent and non-partisan
/ 100% open source
• http://sourceforge.net/projects/tungsten
/ Built-in management
• Manageable from network
• Monitoring integration
/ Routing based on CAP theorem
• Trade off consistency vs. availability vs. partition tolerance
© Continuent 2009

CAP-Based Routing--“Quality of Service”
Connection for Writes Connection for Reads
jdbc:t-router://mysvc/db1 jdbc:t-router://mysvc/db1
?qos=RW_STRICT ?qos=RO_RELAXED
(Data Service)
Strict Session Relaxed
Consistency Consistency* Consistency
Replication
Slave
Master Slave
(latency) Slave
*In progress
© Continuent 2009

Services and Data Sources
/ SQL Router connects to services, not hosts
/ Services are composed of data sources
/ Configuration stored in CLUSTER_HOME directory
$CLUSTER_HOME/
services/
mysvc/
datasource/
db1.properties
db2.properties
db3.properties
replicator/
/ Configuration updated by administrative commands
© Continuent 2009

Administration and Monitoring
/ SQL Router library has JMX ports for administration
/ Update status of data sources using rmctl program:
sql-router[mysvc:ONLINE]> db2 offline
SENT NOTIFICATION: DATASTORE db2 offline
sql-router[mysvc:ONLINE]> db1 online
SENT NOTIFICATION: DATASTORE db1 online
sql-router[mysvc:ONLINE]> db3 online
SENT NOTIFICATION: DATASTORE db3 online
/ Listeners for monitoring events
• Use UDP or group communications or…
• Automatically take data sources online/offline
© Continuent 2009

Does It Work with Non-Java Programs?
/ Yes
/ Use Tungsten Connector as front end
/ Full circle back to better SQL proxies
© Continuent 2009

Tungsten Drilldown – SQL-Router
© Continuent 2009

Roadmap
/ Upgraded monitoring
• Create/remove data sources automatically from monitoring data
• Specify maximum permitted latency
/ Session consistency
/ Partitioning / Sharding
• Route databases to different servers
© Continuent 2009

Contact Information
HQ and Americas EMEA and APAC
560 S. Winchester Blvd., Suite 500 Lars Sonckin kaari 16
San Jose, CA 95128 02600 Espoo, Finland
Tel (866) 998-3642 Tel +358 50 517 9059
Fax +358 9 863 0060
Fax (408) 668-1009
My e-mail: robert.hodges “at” continuent.com
Commercial solutions:
http://www.continuent.com
Tungsten open source stack:
http://community.continuent.com
http://sourceforge.net/projects/tungsten
© Continuent 2009