Building Databases for Multi-Tenant Applications - Large scale applications require sharding to keep up with increased traffic. The simplest and most flexible way to shard is at the schema level. This talk will explain the basics of Tungsten Replicator, installing bi-directional replication between database servers, options for global deployment and best practices when you start sharding. For more information on Tungsen Replicator, visit http://code.google.com/p/tungsten-replicator/.

1. Scaling to Meet Application Demand
Jeff Mace
©Continuent 2012

2. Agenda
• MySQL vs Tungsten Replication
• Simple Replication with demo
• Advanced Replication
• Best Practices
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3. Tungsten Replication
• Compatible with MySQL 5.0+
• Compatible with most MySQL branches
• Crash safe if you use InnoDB
• Replicate between different versions
• Replicate from multiple masters into one
server
• Filter replication traffic in real time
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4. MySQL Replication
Master DB Binary Log Relay Log SQL Slave DB
Tungsten Replication
Binary Log Extractor Transactio Transactio Applier
n History n History
Master DB Slave DB
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5. I have a great idea for a website!
• Rapid prototype ha-proxy
• Load-balanced web
servers
• Single database
server
• Single schema design
Master DB
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6. But what if something goes wrong?
• Stand-by slave ha-proxy
• Can write to it if
the first server
fails
• Extremely difficult
to restore the
primary master
Master DB Slave DB
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7. Simplifying the restore process
• Replication
position ha-proxy
automatically
saved in backups
• Ensure all writes
have been made
on the slave
before switching
to it
Master DB Standby Master
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8. Installation - db1
tools/tungsten-installer
--master-slave
--home-directory=/opt/continuent
--hosts=db1
--master-host=db1
--service-name=alpha ...
/opt/continuent/tungsten/tools/configure-service
-C --role=slave
--master-thl-host=db2
--datasource=db1
--service-type=remote
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9. Installation - db2
tools/tungsten-installer
--master-slave
--home-directory=/opt/continuent
--hosts=db2
--master-host=db2
--service-name=bravo ...
/opt/continuent/tungsten/tools/configure-service
-C --role=slave
--master-thl-host=db1
--datasource=db2
--service-type=remote
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10. Demo
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11. I need more than two servers
Master DB Master DB
What if this link fails?
Master DB
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12. The safer way to add servers
all-masters star-schema
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13. How do I avoid conflicting
updates?
• Writes to many servers can cause conflicts
• Identify a master server for each schema
• All updates are made to that server
• Replication propagates the changes to
remaining servers
• Reads must be made from the master
server
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14. Supporting Application Growth
• Optimize MySQL
• Utilize replicas for read-scaling
• Implement sharding for write-scaling
• Plan for failover
• Monitor everything
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15. Planning for Sharded Databases
• Build your application to be shard-aware
• Don’t use foreign keys that cross schemas
• Minimize DML statements that use
multiple schemas
• Set the schema via the ‘use’ command
• Build a fan-in server for reporting
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16. Fan-In Replication
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17. Identifying Shards
• Find a logical, or convenient, boundary
between groups of users
• Balance individual shard size with the
overall number of shards
• If necessary, utilize a single schema to
assign a shard ID to each user
• Alphabetic distribution is not guaranteed
to be even
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18. From Replication to Managing Data
• Tungsten Replicator moves data
• It does not ensure databases are:
• Protected from failures
• Easy to administer
• Fully utilized
• To manage data you need cluster
management
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19. What did we learn?
• Replication is important to ensure
availability
• Some topologies over greater stability
• Sharding provides the flexibility to
implement many replication topologies
• Growth is supported by proper planning
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20. Jeff Mace
jeff.mace@continuent.com
560 S. Winchester Blvd. Suite 500
San Jose, CA 95128
Tel (866) 998-3642
Fax (408) 668-1009
http://www.continuent.com
http://code.google.com/p/tungsten-replicator
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