How can you improve database query performance without changing the schema?

1 Use indexes

Indexes are data structures that help the database find and access data faster by creating pointers to specific rows or columns. They can speed up queries that filter, sort, join, or group data by reducing the number of scans or comparisons needed. However, indexes also have some drawbacks, such as taking up extra space, slowing down insertions and updates, and requiring maintenance. Therefore, you should use indexes wisely and only on columns that are frequently used in queries, have high selectivity, and have low volatility.

2 Avoid unnecessary columns

When writing a query, you should only select the columns that you need for your output or analysis, and avoid using the asterisk (*) operator that returns all columns. This can improve query performance by reducing the amount of data that needs to be transferred, processed, and stored. It can also prevent potential errors or conflicts if the schema changes in the future. Additionally, you should avoid selecting duplicate or redundant columns that provide the same information or can be derived from other columns.

3 Limit the data

Another way to improve query performance is to limit the amount of data that you retrieve or manipulate by using filters, conditions, or aggregations. For example, you can use the WHERE clause to specify criteria that the data must meet, the LIMIT clause to restrict the number of rows returned, or the GROUP BY clause to summarize the data by categories. These techniques can help you focus on the relevant data and eliminate the unnecessary or irrelevant data that can slow down your query.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?