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.

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。

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After the database is created, you'll create a table, then add some columns.

在创建数据库之后，将创建一个表，然后添加一些列。

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Because this restriction is removed, even if the database is not created in UTF-8, a user can alter a table to add an XML column or create a new table with XML columns.

由于去掉了这个限制，即使数据库不是用utf - 8格式创建的，用户也可以更改一个表以添加xml列，或者创建一个包含xml列的新表。

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