我们可以在Sql Server 2005中的nvarchar(MAX)列上添加Index [英] Can we add Index on nvarchar (MAX) column in Sql Server 2005
问题描述
Hello Everyone,
今天我在某处读到使用索引意味着提高你的应用程序性能。
这听起来很棒,但我遇到了简单的问题。
我有1列有nvarchar(MAX)数据类型,包含大约30k记录。
记录已按升序排序。
我试图通过使用索引对话框来放置索引。但我没找到nvarchar列。我只得到整数作为数据类型的列。
1)索引是否支持NVARCHAR数据类型?
2)我真的需要添加已经排序的列上的索引?
问候
Rohit更多
< blockquote>首先是数据(已经排序?我对此表示怀疑),无论如何...
CREATE TABLE [cpqa]。[tbl_RM_maxNvarchar](
[data] [ nvarchar](323)
)
INSERT INTO [cpqa]。[tbl_RM_maxNvarchar]
VALUES('transworldairlines')
现在该已排序表的索引版本的目标。
CREATE TABLE [cpqa]。[tbl_RM_maxNvarcharX](
[x] [int] IDENTITY(1, 1),
[数据] [nvarchar](323)
)
INSERT INTO [cpqa]。[tbl_RM_maxNvarcharX]
SELECT * FROM [cpqa]。[tbl_RM_maxNvarchar]
执行此查询:
SELECT * FROM [cpqa]。[tbl_RM_maxNvarcharX]
得到这个结果:
x data
~~~~~~~~~~~~~~~~~~~~~~~
1 transworldairlines
And最后使用ORDER BY [x] ASC进行排序。
Hello Everyone,
Today I read somewhere that using index means improving your application performance.
It sounds great but I stuck in simple problem.
I have 1 Column which has nvarchar(MAX) datatype and contains around 30k records.
Records are already sorted in ascending.
I tried to put index by using Indexing dialog. but I didnt find out nvarchar column. I got only columns which has integer as datatype.
1) Does indexs support NVARCHAR datatype?
2) Do I really need to add index on column which is already sorted?
Regards
Rohit More
First the data (already sorted? I doubt it), anyway ...
CREATE TABLE [cpqa].[tbl_RM_maxNvarchar]( [data][nvarchar](323) ) INSERT INTO [cpqa].[tbl_RM_maxNvarchar] VALUES('transworldairlines')
Now the target for an indexed version of that "sorted" table.
CREATE TABLE [cpqa].[tbl_RM_maxNvarcharX]( [x][int]IDENTITY(1,1), [data][nvarchar](323) ) INSERT INTO [cpqa].[tbl_RM_maxNvarcharX] SELECT * FROM [cpqa].[tbl_RM_maxNvarchar]
Execute this query:
SELECT * FROM [cpqa].[tbl_RM_maxNvarcharX]
And get this result:
x data ~~~~~~~~~~~~~~~~~~~~~~~ 1 transworldairlines
And finally sort using ORDER BY [x] ASC.
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