SQL performance tuning can be an extremely complicated task, especially where data in huge quantities is concerned. When implementing queries to insert data in large quantities, even the tiniest of changes can have a major impact on performance – for better or for worse.
If you are new to databases, you may be wondering what SQL performance tuning is and how you can use it with sound knowledge of the fundamentals and a few tricks up your sleeve. In this blog, you will find some fundamental techniques for SQL tuning to improve performance of SQL query being entered in the database.
Techniques to Improve the Performance of SQL Queries
Consider these five tips and techniques to enhance database performance –
Indexes are quite effective in SQL tuning but are often overlooked at the time of development. Basically, an index is a data structure that can boost data retrieval speeds in tables by supplying quick random lookups and prompt access to requested records. This implies that once you have made an index, selecting, SQL performance monitoring, and sorting operations are faster.
They are also useful in defining a primary key that will prevent other columns from having the same values. Naturally, database indexing is a vast topic that deserves its own set of blogs, but for now, it is important to understand that the aim is to index the larger columns intended for searching and ordering.
- Keep in mind, however, that indexes must be modified after INSERT, UPDATE, and DELETE operations, which means they could actually worsen the performance of the database if your tables are receiving a large number of these commands.
- Furthermore, Database Administrators usually discard their indexes before executing gigantic batch inserts involving millions of rows, to hasten the insertion process. Once the task is complete, they then create the indexes all over again. It is important to remember, in such cases, that when the indexes are dropped in this manner, it affects all the queries being executed in that table. Hence, to improve performance of SQL query, this approach is typically taken in certain situations that require a single sizable insertion.
Execution Plan Tool in SQL Server
This tool helps create indexes and it shows all the data retrieval techniques selected by the query optimizer. There are walkthroughs available that will help newcomers learn more about this tool.
- If you are using the SQL Server Management Studio, you can fetch the execution plan by pressing on Ctrl+M to select the “Include Actual Execution Plan” option before executing your query. This leads to a third tab named “Execution Plan” that will show any missing indexes that it has detected.
Steer Clear of Coding Loops
Suppose you need to insert a thousand queries in your database in one go. In that case, you may be tempted to do it using a loop but you must, in fact, refrain from doing so.
- Instead, consider changing the snippets containing the loop in unique INSERT or UPDATE statements that have additional rows and values.
- Make sure that your WHERE clause avoids updating the stored value if it matches the existing value. Such a trivial optimization can dramatically improve performance of SQL query by updating only hundreds of rows instead of thousands.
Checking Whether a Record Exists
This is a handy SQL optimization approach that concerns the use of EXISTS().
- In case you want to know if a certain record is present in the database, make a preference for EXISTS() instead of COUNT(). That’s because EXISTS() can give you much better performance with more coherent code as it leaves the table the moment it gets the data it needs. On the other hand, COUNT() scans the whole table every single time, counting up each and every entry that matches your condition.