如果一个应用程序执行时的性能不合格，较为可取的做法通常是添加更多的列到现有的索引中，或者为一个表添加新的索引，这种做法是首选。

If an application is not performing adequately, it is generally more desirable to add more columns to an existing index, or add new indexes to a table as your first options.

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对于示例场景，在应用程序投入生产的数月之后，为应用程序添加了新功能(包括新sql)，现在需要部署该应用程序。

For the example scenario, a few months after the application has been in production, new function (including new SQL) is added to the application, which now needs to be deployed.

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将应用程序定义为服务的集合，可帮助进行重用和减少与添加新业务服务相关的变更影响。

Defining your application as a collection of business services AIDS reuse and reduces the impact of the change associated with adding new business services.

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