Can unique index be dropped?
A primary key or unique key index cannot be explicitly dropped. You must use one of the following methods to drop it: If the primary index or unique constraint was created automatically for the primary key or unique key, dropping the primary key or unique key causes the index to be dropped.
Can a clustered index also be a unique index?
Yes, a clustered index can also be a unique index. You can create clustered indexes on tables by using SQL Server Management Studio or Transact-SQL. With few exceptions, every table should have a clustered index. A clustered index can also be created on a view.
How do I drop unique index in SQL?
In Object Explorer, right-click the table with the unique constraint, and click Design. On the Table Designer menu, click Indexes/Keys. In the Indexes/Keys dialog box, select the unique key in the Selected Primary/Unique Key and Index list. Click Delete.
How do you make a unique index non-unique?
There’s no way to alter a non-unique index to be unique. Remember that a unique index is a form of constraint. You’re saying that there can only be one row for each set of values in the column list. In the general case, this requires you to use clean the data before you can apply the constraint.
Can we create index on duplicate values?
Yes, you can create a clustered index on key columns that contain duplicate values. For example, you might decide to create a clustered index on the LastName column of a table that contains customer data.
What happens when you drop the Index in SQL Server?
Reading a slightly larger index will take slightly more time: if a query didn’t need that QuotaItemDriverID field, it still has to pull it off the disk in order to perform the query. However, dropping the index pays off during inserts/updates/deletes, because it’s one less index SQL Server has to manage.
How to detect duplicate or overlapping indexes in Excel?
To detect both duplicate indexes AND overlapping indexes, we can modify the query we wrote earlier by using some string manipulation: Only two adjustments were needed to change our query to look for similar data, rather than identical data. First, we removed the equality check on the included columns list.
Why are there unused indexes in SQL Server?
Find unused indexes – these are indexes the SQL Server engine says it’s not using. Unused indexes incur a speed penalty because SQL Server still has to add/update the indexes as records change, so they make writes slower. Find missing indexes – these are indexes SQL Server wishes it had available.
Why are there so many duplicate indexes in SQL Server?
SQL Server has no safeguards against indexes that duplicate behavior, and therefore a table could conceivably have any number of duplicate or overlapping indexes on it without your ever knowing they were there! This would constitute an unnecessary drain on resources that could easily be avoided.