tuning in sql server - views

问题

I created a view in sql server 2012, such as:

create myview as
select mytable2.name
from mytable1 t1
join myTable2 t2
on t1.id = t2.id

I want that join table1 and table2 will be with correct index (id), but when I do:

select * from myview
where name = 'abcd'

I want that the last select will be with index of column 'name'.

What is the correct syntax in sql server with hints (tuning), that do the best run, as I have described?

I want to force using of index for join purpose only (the column = id), and forcing index name when doing:

select name from myview 
where name = 'abcd'.

Something like

create myview as
select mytable2.name
/* index hint name on  column name */
from mytable1 t1
join myTable2 t2
/* index hint name on  column id - just for join */
on t1.id = t2.id

I don't want to force end-user that uses the view add hint when doing the view - just bring him the view as his with proper index hints. (or, if it is not possible - how can I do that).

Need samples, please.

Thanks :)

回答1:

Indexes in SqlServer are built from two sets of columns. Create index IX on table B (Filter Columns,Sorting Columns) INCLUDE (Additional columns to be included).

And when selecting from views, the optimizer will incorporate indexes on the referenced tables.

The first set is the indexing table itself. Best practice is to place the columns by which you filter first, and then the columns by which you sort. The second set (Include), are additional columns you add to the indexing table, so all the data you require is in the index (to prevent key look ups - dpending on your table design).

In your case, the order will be 1) Go to MyTable2 by name, and get all of the matching ID's. 2) With the Id's from step 1, find the matching ID's in Mytable1

Your indexes should be :

1) An index on Table2(Name,ID) or Table2(Name)Include(ID)

2) An index on Table1(ID)

There shouldn't be any hint used in this case. And in general, you should avoid using hints.

回答2:

I reckon creating an Index on the Name column would use the index, when selecting from view with the above shown where clause, you dont have to explicitly give any query hints to make that view use the index.

Index should be something like...

Index

CREATE NONCLUSTERED INDEX [IX_MyTable1_Name] 
ON [dbo].[myTable2] ([CompanyName] ASC)
GO

View Definition

CREATE VIEW myview 
 AS
SELECT t2.name  --<-- Use alias here since you have alised your table in from clause
FROM mytable1 t1
INNER JOIN myTable2 t2 ON t1.id = t2.id

来源：https://stackoverflow.com/questions/28136403/tuning-in-sql-server-views

标签

sql-server

hint