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增加varchar字段的大小时SQL Server 2005索引重建

[英]SQL Server 2005 Index rebuild when increasing the size of a varchar field

原文 2010-10-06 01:20:57 5 1 sql/ sql-server-2005/ indexing/ varchar/ rebuild

I have a 12 varchar(50) fields in a table of about 90 million rows that I need to increase to varchar(100) in length. 我在大约9000万行的表中有12个varchar（50）字段，需要将其长度增加到varchar（100）。 Each of these fields has an index (with only the one field as a member). 这些字段中的每个字段都有一个索引（只有一个字段作为成员）。 If I increase the length of the varchar fields, will the indexes either need to be rebuilt (or would be rebuilt automatically), or would the statistics become out of date? 如果增加varchar字段的长度，是否需要重建索引（或将自动重建索引），或者统计信息会过时？

I don't have a reasonably sized test system test (or perhaps dont know how to see if the indexes were rebuilt or statistics need to be recomputed). 我没有适当大小的测试系统测试（或者也许不知道如何查看是否重建了索引或需要重新计算统计信息）。

Thanks 谢谢

1 个解决方案

Statistics are based on what is in columns, not their size, so your statistics won't become out of date. 统计信息基于列中的内容而不是其大小，因此您的统计信息不会过时。

Bear in mind that sometimes when you alter a column, SQL server will add a new column to the table and drop the existing one, so it will have to rebuild the index in that case anyway. 请记住，有时当您更改一列时，SQL Server会在表中添加一个新列并删除现有的列，因此无论如何都必须重建索引。

Despite searching I can't categorically say whether you have to rebuild indexes, but I would rebuild regardless (as this should be occuring as part of your normal maintenance, assuming this table is not read-only or very low writes) 尽管进行了搜索，但我无法明确地说是否必须重建索引，但是无论如何我都将重建（因为这应该是正常维护的一部分，假设此表不是只读的或写得很少）

BTW, having a seperate index on each of those columns might not be optimal. 顺便说一句，在那些列的每一列上都有单独的索引可能不是最佳的。 Have you profiled your query workload? 您是否配置了查询工作量？