Read this quick guide of how to optimize SQL queries.

Quick guide on optimizing SQL Queries

Organizations and businesses that work without a complete data warehouse or a proper technical team that can deal in an analytics database, only have the option of the production database. But when it comes to a production database, the first thing that should be pondered over is the optimization of SQL queries.

This is very important to understand because an inefficient or irrelevant query may result in loss of service or slowing down the performance of the system. Let’s find out the ways that can help in query optimization in SQL Server.

1. Business Requirements

Defining the requirements of the business is the prime thing before beginning with SQL queries. These requirements could be related to the following:

  • Figuring out who the relevant stakeholders are as an indulgence with the entire team is a must when developing the query.
  • The query should be purposeful and should focus on the outcomes that are relevant to your objective.
  • Do ask the team the 5Ws to generate logical requirements.

2. SELECT Field

Make sure you are using the SELECT statement only and not the SELECT* (which indicates selecting the entire data). This is important because when you select all the data, it may contain unnecessary information whereas, choosing SELECT only will result in querying only the relevant information that is required for the work objective.

3. Use Wildcards

If you are willing to search plaintext data for example names or cities the use of wildcards helps in searching the widest data. Even though this results in irrelevant search, you may use a leading wildcard with a mixture of ending wildcard which will help in reaching out to search all the information for a relevant match within the desired field.

4. Use LIMIT

When you are running a query for the first time, you need to ensure beforehand that the results will be significant by using the query LIMIT. This particular statement helps in returning only the specified records which helps to prevent taxing the production database with a big query to figure out whether the query requires any edit or not.

5. Run Queries on Off Time

To lessen the query impact on a production database, it is suggested to run the queries at an off time when there are very fewer users available as this helps in quick running and achieve results in the right manner. Typically the recommended time is 3 am to 5 am. Moreover, if your query contains the below criteria, there are more chances to have it run smoothly at the middle of the night:

  • Selecting from large tables (>1,000,000 records)
  • Nested subqueries
  • Multiple schema queries
  • Cartesian Joins or CROSS JOINs
  • Wildcard searches in long text or memo fields
  • Cartesian Joins or CROSS JOINs

I hope the above-stated guidelines helped you in optimizing your SQL queries in order to maximize the performance. These techniques are known to ensure that proper maintenance of the database set up while indicating quality and performance.