Learn SQL Database Programming

Understanding when to create indexes

You should create indexes for regularly used queries. Don't create indexes that don't have a use case for the queries being executed against a table. Don't guess at what indexes a table needs. Instead, you need to know the queries that are being executed, how often they are executed, and how important they are. Then you can decide how to create indexes based on the conditions used in the WHERE clause and by the columns used in the ORDER BY and GROUP BY clauses.

There is no right number of indexes on a table or columns in your indexes. Generally speaking, too few or too many indexes can make the performance of your database worse. This is why it's important to know what queries are being executed on the ...