How to optimize this SQL query?
In case you have your own slow SQL query, you can optimize it automatically here.
For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:
- Description of the steps you can take to speed up the query.
- The optimal indexes for this query, which you can copy and create in your database.
- An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
- Avoid Calling Functions With Indexed Columns (query line: 8): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. For example, if the column `TABLE_NAME` is indexed, the index won’t be used as it’s wrapped with the function `RIGHT`. If you can’t find an alternative condition that won’t use a function call, a possible solution is to store the required value in a new indexed column.
- Avoid Subqueries (query line: 9): We advise against using subqueries as they are not optimized well by the optimizer. Therefore, it's recommended to join a newly created temporary table that holds the data, which also includes the relevant search index.
The optimized query:
SELECT
INFORMATION_SCHEMA.VIEWS.TABLE_SCHEMA + '.' + INFORMATION_SCHEMA.VIEWS.TABLE_NAME
FROM
INFORMATION_SCHEMA.VIEWS
WHERE
INFORMATION_SCHEMA.VIEWS.TABLE_SCHEMA + '.' + INFORMATION_SCHEMA.VIEWS.TABLE_NAME LIKE 'sec.actions_authorized_%'
AND
RIGHT(INFORMATION_SCHEMA.VIEWS.TABLE_NAME, NULLIF(CHARINDEX('_', REVERSE(INFORMATION_SCHEMA.VIEWS.TABLE_NAME)), 0) - 1) NOT IN (
SELECT
DISTINCT CAST(session.empid AS NVARCHAR (20)) FROM
session
)