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Chapter 31: Managing Data in Windows Azure SQL Database
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as imposing a heavy load or fi lling up the transaction logs (don’t overburden IOPS or CPU
cycles, for instance).Thus, resources are monitored, including yours. The entire health of the machine is always
monitored by the throttling engine. Things such as log size, log write duration, CPU usage,
and database size (among others) are continuously monitored. If SQL Database determines
that limits are exceeded, SQL Database may reject your connection for 10 seconds at a time.
Continuous violations may result in the permanent rejection of read and writes. So play nice.Load Balancing
Load balancing is another area where SQL Database shines. Load balancing in SQL Database
is achieved by moving the databases within the physical machines, or across machines,
based on periodic audits of system usage. However, you need to remember that SQL
Database is a shared environment, and as such is it impossible to predict workloads of
each subscriber. There are no performance guarantees, but performance is still crucial and
important to SQL Database. Thus, when a new database is added to SQL Database, the Load
Balancer determines the location of the primary and secondary replicas based on the cur-
rent load of the machines in the data center.However, the database may not remain there. SQL Database is continuously monitoring the
loads of the servers and may move a primary to a machine with less load to ensure a prop-
erly performing database.Migrating Data to SQL Database
So you want to move one or more of your applications and their databases to the cloud.
It’s a noble idea. More than likely, you’re in the same category as countless others who are
looking into moving applications into the cloud: You don’t want to start from scratch. You’d
rather migrate an existing application to the cloud, but you aren’t sure about the steps
necessary to do so, or the technologies available to help in the process. This section
discusses three tools from Microsoft that come with SQL Server to help with your database
migration needs:■ Generate and Publish Scripts Wizard■ (^) SQL Server Integration Services (SSIS)
■ Bcp utility
In addition to these three tools, a free utility found on CodePlex called the SQL Database
Migration Wizard, which provides a wizard-driven interface to walk you through migrating
your database and data to SQL Database, is briefl y covered.
The examples in this chapter use SQL Server 2012. These examples also work with SQL
Server 2008 R2.
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