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 Selecting Unnecessary Columns (query line: 2): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Selecting redundant columns may result in unnecessary performance degradation.
- 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 table2_idx_table1id ON Table2 (Table1ID);
CREATE INDEX table3_idx_table1id ON Table3 (Table1ID);
The optimized query:
SELECT
T.*
FROM
dbo.Table1 T
LEFT JOIN
Table2 T2
ON T.ID = T2.Table1ID
LEFT JOIN
Table3 T3
ON T.ID = T3.Table1ID
WHERE
T2.Table1ID IS NOT NULL
OR T3.Table1ID IS NOT NULL