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Why is the index not making execution faster?
Index not making execution faster, and in some cases is slowing down the query. Why is it so? I was experimenting with indexes to speed up things, but in case of a join, the index is not improving the query execution time and in some cases it is slowing things down. The query to create test table and fill it with data is: CREATE TABLE [dbo].
Which is query slows down due to the index?
Now the query which slows down due to the index (the query is meaningless since it is created for testing only): With clustered index enabled: (1 row (s) affected) Table ‘IndexTestTable’. Scan count 4, logical reads 60, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Which is better clustered index or nonclustered index?
The main thing you are missing is that although the plan using the nonclustered index has a lower estimated cost according to the optimizer’s model, it has a significant execution-time problem. If you look at the distribution of rows across threads in the plan using the Clustered Index, you will likely see a reasonably good distribution:
Are there query hints to affect row distribution among threads?
There are no query hints to affect row distribution among threads, the important thing is to be aware of the possibility and to be able to read enough detail in the execution plan to determine when it is causing a problem.
Why is this query not using my nonclustered index?
The first query uses the clustered index, the second query uses my non-clustered index. My question is two parts: Why, since both queries have a WHERE clause on the [DateEntered] field, does the server use the clustered index on the first, but not the second?
How long does it take to create an index in SQL Server?
If index is relatively wide – it can take from minutes to hours. if you have your DB on Enterprise Edition of Sql Server, than you can choose to create an index WITH ONLINE=ON – it will take a little bit more time and space to complete, but will not stop other processing with the table involved