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 LIKE Searches With Leading Wildcard (query line: 7): The database will not use an index when using like searches with a leading wildcard (e.g. '%'). Although it's not always a satisfactory solution, please consider using prefix-match LIKE patterns (e.g. 'TERM%').
- Avoid LIKE Searches With Leading Wildcard (query line: 9): The database will not use an index when using like searches with a leading wildcard (e.g. '%'). Although it's not always a satisfactory solution, please consider using prefix-match LIKE patterns (e.g. 'TERM%').
- Avoid LIKE Searches With Leading Wildcard (query line: 10): The database will not use an index when using like searches with a leading wildcard (e.g. '%'). Although it's not always a satisfactory solution, please consider using prefix-match LIKE patterns (e.g. 'TERM%').
- Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
Optimal indexes for this query:
CREATE INDEX exchanges_idx_exchangesetid ON Exchanges (ExchangeSetId);
The optimized query:
SELECT
TOP 1 Exchanges.ClassId
FROM
Exchanges
WHERE
Exchanges.ExchangeSetId = 1
AND Exchanges.BasePrefix LIKE
left(@BaseNumber, 3) + '%'
AND @BaseNumber LIKE Exchanges.BasePrefix + '%'
AND @DestNumber LIKE Exchanges.DestPrefix + '%'