Download Transactional Replication

Distributing Data for
Availability and Scalability
Don Vilen
Program Manager
SQL Server
Microsoft Corporation
Agenda
 Replication Technology Positioning
 SQL Server Replication Customer
Scenarios
 Upgrade Strategy
 Key Improvements in SQL Server 2005
Replication
SQL Server Replication
A Spectrum of Solutions
Increasing autonomy
Increasing consistency
Automatic conflict detection &
resolution
Conflicts are avoided through partitioning or twophase commit
Merge
Replication
Transactional
Replication
Queued
Updating
Subscribers
Peer-to-Peer
Immediate
Updating
Subscribers
Linked
Servers and
Microsoft
Distributed
Transaction
Coordinator
Replication Technologies
Server Scenarios
 Transactional Replication
 Best choice continuously synchronizing databases to
support scaling out query workloads
 SQL Server Integration Services (was DTS)
 Best choice for performing transformations on data
during transfer between databases
 Database Mirroring
 Best choice for providing database high availability
 Disk / Device Mirroring
 Third-party solutions
 Ensure it meets SQL Server I/O Basics requirements
Mobile Synchronization Comparison
Merge
Replication
Incremental Changes
Conflict detection and resolution
Automatically initialize schema and
Supports large datasets
Query processor locally available
Unique IDs across remote sites
Database constraints locally
Supports heterogeneous databases
Does not affect database schema
Deploy application and db together
Offline
Datasets
Web
Agenda
 Replication Technology Positioning
 SQL Server Replication Customer
Scenarios
 Upgrade Strategy
 Key Improvements in SQL Server 2005
Replication
Customer Scenarios
 Offloading reporting and Data





Warehousing
Database scale out for websites
Empowering mobile users
Enabling Point of Sale applications
Consolidating and distributing regional
data
Integrating heterogeneous data
Reporting and Data
Warehousing
 Reporting databases are
continuously
synchronized in near
real-time with one or
more source OLTP
databases
 Reporting and Staging
user queries are
offloaded from the OLTP
databases
 Reporting data can be a
subset of source tables
and columns and also
indexed differently
 Read-only replicas
Database Scale Out
 Queries scaled out
Chicago
London
Tokyo
(often geographically)
similar to reporting
cases
 But databases
replicate reciprocally
and are writable
 Redundancy provides
fault tolerance and
lowers maintenance
downtime
 Online upgrades
possible
Mobile CRM / SFA
Customer Relationship Management
Sales Force Automation
 Key Traits
 Subset of data
from server
 Conflicts
 Data
realignment
 Business Logic
Point of Sale
 Key Traits
 High latency low
bandwidth
network
 Need low cost
software and
administration
 Sync at
scheduled times
 Upload orders
then remove
Regional Replication
 Central headquarters
data replicated to
1200 stores
 Each store also
replicates between
two databases to
provide a backup in
case one fails
 Database
administrators are
centralized
Regional Replication
 Each ship contains a
SQL Server database
SQL Server
SQL Server
Transactional Replication
Customized
Replication
Logic
Headquarters
SQL Server
 When the ship docks,
it replicates to the
headquarters’
database
 Replication was
customized to
perform additional
processing when
synchronizing
Oracle Replication
Manufacturing System
SQL Server 2005
Transactional
Replication
Oracle
10G
 SQL Server 2005
Transactional Replication
 SQL Server synchronized
with Oracle production
line system in near realtime
 Used to monitor
manufacturing
 Reporting: Quality
control, status, and “what
if” queries spread across
multiple databases
Top SQL Server Customers
Transactional Replication
[Click logo for case-study]


15+ TB data in multiple systems, multiple hospitals
Replicates to meet HA requirements


Runs many core trading applications on SQL Server
Replicates data to integrated multiple trading systems


Leading discount retailer, SQL Server in 1200 stores
Replicates data up and down between stores & HQ
Agenda
 Replication Technology Positioning
 SQL Server Replication Customer
Scenarios
 Upgrade Strategy
 Key Improvements in SQL Server 2005
Replication
Upgrade: Replication
 SQL Server 2005 Express Edition does not
support Merge publishing
 SQL Server 2000 MSDE did support it
 SQL Server Express requires custom code
or Windows Sync Manager to synchronize
 If you run agents as DBO, now requires a
job_login and job_password to be added to
replication scripts
Upgrade: Merge Replication
 Snapshot must be executed after setup
 Upgrade order
 Distributor, publisher, subscriber
 Applications must be built on Visual Studio
2005 to use programming APIs
 SQL Server 2005 subscribers outperform
previous versions
Agenda
 Replication Technology Positioning
 SQL Server Replication Customer
Scenarios
 Upgrade Strategy
 Key Improvements in SQL Server 2005
Replication
Database Schema Changes
 One of the key problems when replicating
data is accommodating schema changes
without disrupting replication
 SQL Server 2005 supports adding,
dropping, and altering columns without
stopping replication
 Alter table alter column ( foo int )
 Tables and other supported objects can
also be added or dropped
Database Scale-Out Requirements
 Maximize website uptime
 Database upgrades or failures shouldn’t bring down
the application system
 Database upgrades should be done without outages
 Scale query workloads beyond what’s possible
with a single database
 Must be possible to add or remove databases without
an outage while also maintaining consistency
 SQL Server 2005 Peer-to-Peer Replication
provides this capability
 Workbench wizard allows easy replication setup
Peer-to-Peer Topology
London
Chicago
Logreader
Agent
Logreader
Agent
Transactional
Replication
Dist
DB
Distribution
Agent
Dist
DB
Tokyo
Logreader
Agent
Dist
DB
Distribution
Agent
Distribution
Agent
Replicating Large Databases
 The key problem with replicating large
databases is initializing the subscriber
 This can be time-consuming and requires
downtime to ensure consistency of the
replicated database
 SQL Server 2005 has support for using an
existing database backup to perform the
initial synchronization
 Initialization with a backup
 Changes that have occurred on the source
system after the backup are tracked and
synchronized automatically
Synchronizing Data Over the Web
 Key customer drivers
 Wireless increasingly pervasive
 Virtual Private Network (VPN) too expensive
or complicated for organizations
Internet
Information
Services (IIS)
Subscriber
-InternetUrl
https://myserver.mydomain.com
Firewall
Replisapi.dll
Publisher/Distributor
Logical Records
 Problem
 Merge replication tracks changes row by row
 An actual order is represented in the
Customers, Orders, OrderDetails tables
 Disconnection during sync results in
incomplete order on server
 Solution
 Logical records create a logical consistency
unit between tables
 All three changes are sent or nothing at all
Business Logic
 APIs to allow custom programming during
the synchronization of changes
 Allows developer to take custom actions
on different states of data
 Publisher insert, update, delete
 Subscriber insert, update delete
 Business Logic is registered on a per
article basis
Merge Performance Comparison
Rows Per Second
3500
3296
3000
2500
1968
2000
1751
1656
1500
1000
848
500
0
SQL 2000
SQL 2005
backcompat mode
SQL 2005 PreComputed
Partitions
Field Force, POS
Applications
Reference Data
Scalability Comparison
Synchronization Time
1000
900
Average Sync Time
800
700
600
500
400
300
200
100
0
SQL 2000
SQL 2005
20
50
# of concurrent syncs
100
Monitoring
Goals
 Provide answers to common questions:
 Why is the system slow?
 How long until it catches up or finishes?
 Where are the potential problems?
Oracle Publishing
 Designed specifically for Oracle Publishers
 v8+ on any operating system
 Administered like SQL Server, from SQL Server
 No Oracle-side software install necessary
 Requires minimal knowledge of Oracle
 Leverages existing SQL Server skills
 Standard Transactional and Snapshot Publications
Transactional
Replication
ORACLE
SQL Server
2005
Distributor
Subscribers
Many Other New Features
 Transactional tracer token
 Merge Article types
 Tables, views, stored procedures, userdefined functions, and stored procedure
execution
 Resumable snapshot
 Parallelism and contention improvements
 Wizards simplified
 Replication Management Objects (RMO)
managed replication APIs
 Security
Summary
 Replication Technology Positioning
 SQL Server Replication Customer
Scenarios
 Upgrade Strategy
 Key Improvements in SQL Server 2005
Replication
For More Information
 Books Online Replication Section
 Merge Replication
 White Paper
 Oracle
 Oracle Publishing Quick Start Whitepaper
 SQL Server 2005 Oracle Replication Overview
 Peer-to-Peer
 Books Online
© 2006 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.